#pragma once

#include "nasal_err.h"
#include "nasal_builtin.h"
#include "nasal_opcode.h"

#include <iomanip>
#include <list>
#include <stack>
#include <unordered_map>

class codegen {
private:
    u16 fileindex;
    error& err;
    const string* file;
    std::stack<u32> in_iterloop;
    std::unordered_map<f64,u32> num_table;
    std::unordered_map<string,u32> str_table;
    std::vector<f64> num_res;
    std::vector<string> str_res;
    std::vector<opcode> code;
    std::list<std::vector<i32>> continue_ptr;
    std::list<std::vector<i32>> break_ptr;

    // symbol table
    // global : max STACK_DEPTH-1 values
    std::unordered_map<string,i32> global;
    // local  : max 32768 upvalues 65536 values
    // but in fact local scope also has less than STACK_DEPTH value
    std::list<std::unordered_map<string,i32>> local;

    bool check_memory_reachable(const ast&);
    void check_id_exist(const ast&);
    
    void die(const string& info, const span& loc) {
        err.err("code", loc, info);
    }

    void regist_num(const f64);
    void regist_str(const string&);
    void find_symbol(const ast&);
    void add_sym(const string&);
    i32 local_find(const string&);
    i32 global_find(const string&);
    i32 upvalue_find(const string&);

    void gen(u8, u32, u32);

    void num_gen(const ast&);
    void str_gen(const ast&);
    void bool_gen(const ast&);
    void vec_gen(const ast&);
    void hash_gen(const ast&);
    void func_gen(const ast&);
    void call_gen(const ast&);
    void call_id(const ast&);
    void call_hash(const ast&);
    void call_vec(const ast&);
    void call_func(const ast&);
    void mcall(const ast&);
    void mcall_id(const ast&);
    void mcall_vec(const ast&);
    void mcall_hash(const ast&);
    void multi_def(const ast&);
    void single_def(const ast&);
    void def_gen(const ast&);
    void multi_assign_gen(const ast&);
    void cond_gen(const ast&);
    void loop_gen(const ast&);
    void load_continue_break(i32, i32);
    void while_gen(const ast&);
    void for_gen(const ast&);
    void expr_gen(const ast&);
    void forindex_gen(const ast&);
    void foreach_gen(const ast&);
    void or_gen(const ast&);
    void and_gen(const ast&);
    void trino_gen(const ast&);
    void calc_gen(const ast&);
    void block_gen(const ast&);
    void ret_gen(const ast&);

public:
    codegen(error& e): fileindex(0), err(e), file(nullptr) {}
    const error& compile(const parse&, const linker&);
    void print();
    const std::vector<string>& strs()  const {return str_res;}
    const std::vector<f64>&    nums()  const {return num_res;}
    const std::vector<opcode>& codes() const {return code;}
};

bool codegen::check_memory_reachable(const ast& node) {
    if (node.type()==ast_call) {
        const ast& tmp=node.child().back();
        if (tmp.type()==ast_callf) {
            die("bad left-value with function call", node.location());
            return false;
        }
        if (tmp.type()==ast_callv && (tmp.size()==0 || tmp.size()>1 || tmp[0].type()==ast_subvec)) {
            die("bad left-value with subvec", node.location());
            return false;
        }
    } else if (node.type()!=ast_id) {
        die("bad left-value", node.location());
        return false;
    }
    return true;
}

void codegen::check_id_exist(const ast& node) {
    const string& str=node.str();
    for(u32 i=0;builtin[i].name;++i) {
        if (builtin[i].name==str) {
            if (local.empty()) {
                die("useless native function used in global scope", node.location());
            }
            return;
        }
    }

    if (local_find(str)>=0) {
        return;
    }
    if (upvalue_find(str)>=0) {
        return;
    }
    if (global_find(str)>=0) {
        return;
    }
    die("undefined symbol \""+str+"\", and this symbol is useless here", node.location());
}

void codegen::regist_num(const f64 num) {
    if (!num_table.count(num)) {
        u32 size=num_table.size();
        num_table[num]=size;
        num_res.push_back(num);
    }
}

void codegen::regist_str(const string& str) {
    if (!str_table.count(str)) {
        u32 size=str_table.size();
        str_table[str]=size;
        str_res.push_back(str);
    }
}

void codegen::find_symbol(const ast& node) {
    // symbol definition checked here
    // if find a function, return
    if (node.type()==ast_func) {
        return;
    } else if (node.type()==ast_def) { // find definition, check
        if (node[0].type()==ast_multi_id) {
            for(auto& i:node[0].child()) {
                add_sym(i.str());
            }
        } else {
            add_sym(node[0].str());
        }
        find_symbol(node[1]);
    } else if (node.type()==ast_iter) { // find iterator(foreach, forindex), check
        add_sym(node[0].str());
    } else { // check children
        for(auto& i:node.child()) {
            find_symbol(i);
        }
    }
}

void codegen::add_sym(const string& name) {
    if (local.empty()) {
        if (global.count(name)) {
            return;
        }
        i32 index=global.size();
        global[name]=index;
        return;
    }
    if (local.back().count(name)) {
        return;
    }
    i32 index=local.back().size();
    local.back()[name]=index;
}

i32 codegen::local_find(const string& name) {
    if (local.empty()) {
        return -1;
    }
    return local.back().count(name)?local.back()[name]:-1;
}

i32 codegen::global_find(const string& name) {
    return global.count(name)?global[name]:-1;
}

i32 codegen::upvalue_find(const string& name) {
    // 32768 level 65536 upvalues
    i32 index=-1;
    usize size=local.size();
    if (size<=1) {
        return -1;
    }
    auto iter=local.begin();
    for(u32 i=0;i<size-1;++i,++iter) {
        if (iter->count(name)) {
            index=((i<<16)|(*iter)[name]);
        }
    }
    return index;
}

void codegen::gen(u8 op, u32 num, u32 line) {
    code.push_back({op, fileindex, num, line});
}

void codegen::num_gen(const ast& node) {
    f64 num=node.num();
    regist_num(num);
    gen(op_pnum,num_table[num], node.line());
}

void codegen::str_gen(const ast& node) {
    regist_str(node.str());
    gen(op_pstr, str_table[node.str()], node.line());
}

void codegen::bool_gen(const ast& node) {
    f64 num=node.str()=="true"?1:0;
    regist_num(num);
    gen(op_pnum, num_table[num], node.line());
}

void codegen::vec_gen(const ast& node) {
    for(auto& child:node.child()) {
        calc_gen(child);
    }
    gen(op_newv, node.size(), node.line());
}

void codegen::hash_gen(const ast& node) {
    gen(op_newh, 0, node.line());
    for(auto& child:node.child()) {
        calc_gen(child[1]);
        const string& str=child[0].str();
        regist_str(str);
        gen(op_happ, str_table[str], child.line());
    }
}

void codegen::func_gen(const ast& node) {
    // parameter list format check
    bool checked_default=false;
    bool checked_dynamic=false;
    std::unordered_map<string,bool> argname;
    for(auto& tmp:node[0].child()) {
        if (tmp.type()==ast_default) {
            checked_default=true;
        } else if (tmp.type()==ast_dynamic) {
            checked_dynamic=true;
        }
        // check default parameter and dynamic parameter
        if (checked_default && tmp.type()!=ast_default) {
            die("must use default parameters here", tmp.location());
        }
        if (checked_dynamic && &tmp!=&node[0].child().back()) {
            die("dynamic parameter must be the last one", tmp.location());
        }
        // check redefinition
        string name=tmp.str();
        if (argname.count(name)) {
            die("redefinition of parameter: "+name, tmp.location());
        } else {
            argname[name]=true;
        }
    }

    usize newf=code.size();
    gen(op_newf, 0, node.line());
    usize lsize=code.size();
    gen(op_intl, 0, node.line());
    
    // add special keyword 'me' into symbol table
    // this symbol is only used in local scope(function's scope)
    // this keyword is set to nil as default value
    // after calling a hash, this keyword is set to this hash
    // this symbol's index will be 0
    local.push_back({{"me", 0}});

    // generate parameter list
    for(auto& tmp:node[0].child()) {
        const string& str=tmp.str();
        if (str=="me") {
            die("\"me\" should not be a parameter", tmp.location());
        }
        regist_str(str);
        switch(tmp.type()) {
            case ast_id:
                gen(op_para, str_table[str], tmp.line());
                break;
            case ast_default:
                calc_gen(tmp[0]);
                gen(op_deft, str_table[str], tmp.line());
                break;
            case ast_dynamic:
                gen(op_dyn, str_table[str], tmp.line());
                break;
        }
        add_sym(str);
    }

    code[newf].num=code.size()+1; // entry
    usize jmp_ptr=code.size();
    gen(op_jmp, 0, node.line());

    const ast& block=node[1];
    // search symbols first, must use after loading parameters
    // or the location of symbols will change and cause fatal error
    find_symbol(block);
    in_iterloop.push(0);
    block_gen(block);
    in_iterloop.pop();
    code[lsize].num=local.back().size();
    if (local.back().size()>=STACK_DEPTH) {
        die("too many local variants: "+std::to_string(local.back().size()), block.location());
    }
    local.pop_back();

    if (!block.size() || block.child().back().type()!=ast_ret) {
        gen(op_pnil, 0, block.line());
        gen(op_ret, 0, block.line());
    }
    code[jmp_ptr].num=code.size();
}

void codegen::call_gen(const ast& node) {
    calc_gen(node[0]);
    if (code.back().op==op_callb) {
        return;
    }
    for(usize i=1;i<node.size();++i) {
        const ast& tmp=node[i];
        switch(tmp.type()) {
            case ast_callh:call_hash(tmp);break;
            case ast_callv:call_vec(tmp); break;
            case ast_callf:call_func(tmp);break;
        }
    }
}

void codegen::call_id(const ast& node) {
    const string& str=node.str();
    for(u32 i=0;builtin[i].name;++i) {
        if (builtin[i].name==str) {
            gen(op_callb, i, node.line());
            if (local.empty()) {
                die("should warp native function in local scope", node.location());
            }
            return;
        }
    }
    i32 index;
    if ((index=local_find(str))>=0) {
        gen(op_calll, index, node.line());
        return;
    }
    if ((index=upvalue_find(str))>=0) {
        gen(op_upval, index, node.line());
        return;
    }
    if ((index=global_find(str))>=0) {
        gen(op_callg, index, node.line());
        return;
    }
    die("undefined symbol \""+str+"\"", node.location());
}

void codegen::call_hash(const ast& node) {
    regist_str(node.str());
    gen(op_callh, str_table[node.str()], node.line());
}

void codegen::call_vec(const ast& node) {
    // maybe this place can use callv-const if ast's first child is ast_num
    if (node.size()==1 && node[0].type()!=ast_subvec) {
        calc_gen(node[0]);
        gen(op_callv, 0, node[0].line());
        return;
    }
    gen(op_slcbeg,0,node.line());
    for(auto& tmp:node.child()) {
        if (tmp.type()!=ast_subvec) {
            calc_gen(tmp);
            gen(op_slc, 0, tmp.line());
        } else {
            calc_gen(tmp[0]);
            calc_gen(tmp[1]);
            gen(op_slc2, 0, tmp.line());
        }
    }
    gen(op_slcend, 0, node.line());
}

void codegen::call_func(const ast& node) {
    if (!node.size()) {
        gen(op_callfv, 0, node.line());
    } else if (node[0].type()==ast_pair) {
        hash_gen(node);
        gen(op_callfh, 0, node.line());
    } else {
        for(auto& child:node.child()) {
            calc_gen(child);
        }
        gen(op_callfv, node.size(), node.line());
    }
}

/* mcall should run after calc_gen because this operation may trigger gc.
*  to avoid gc incorrectly collecting values that include the memory space(which will cause SIGSEGV),
*  we must run ast[1] then we run ast[0] to get the memory space.
*  at this time the value including the memory space can must be found alive.
*  BUT in fact this method does not make much safety.
*  so we use another way to avoid gc-caused SIGSEGV: reserve m-called value on stack.
*  you could see the notes in `vm::opr_mcallv()`.
*/
void codegen::mcall(const ast& node) {
    if (!check_memory_reachable(node)) {
        return;
    }
    if (node.type()==ast_id) {
        mcall_id(node);
        return;
    }
    if (node.size()==1) { // foreach and forindex use call-id ast to get mcall
        mcall_id(node[0]);
        return;
    }
    calc_gen(node[0]);
    for(usize i=1;i<node.size()-1;++i) {
        const ast& tmp=node[i];
        switch(tmp.type()) {
            case ast_callh:call_hash(tmp);break;
            case ast_callv:call_vec(tmp); break;
            case ast_callf:call_func(tmp);break;
        }
    }
    const ast& tmp=node.child().back();
    if (tmp.type()==ast_callh) {
        mcall_hash(tmp);
    } else if (tmp.type()==ast_callv) {
        mcall_vec(tmp);
    }
}

void codegen::mcall_id(const ast& node) {
    const string& str=node.str();
    for(u32 i=0;builtin[i].name;++i) {
        if (builtin[i].name==str) {
            die("cannot modify native function", node.location());
            return;
        }
    }
    i32 index;
    if ((index=local_find(str))>=0) {
        gen(op_mcalll, index, node.line());
        return;
    }
    if ((index=upvalue_find(str))>=0) {
        gen(op_mupval, index, node.line());
        return;
    }
    if ((index=global_find(str))>=0) {
        gen(op_mcallg, index, node.line());
        return;
    }
    die("undefined symbol \""+str+"\"", node.location());
}

void codegen::mcall_vec(const ast& node) {
    calc_gen(node[0]);
    gen(op_mcallv, 0, node.line());
}

void codegen::mcall_hash(const ast& node) {
    regist_str(node.str());
    gen(op_mcallh, str_table[node.str()], node.line());
}

void codegen::single_def(const ast& node) {
    const string& str=node[0].str();
    calc_gen(node[1]);
    local.empty()?
        gen(op_loadg, global_find(str), node.line()):
        gen(op_loadl, local_find(str), node.line());
}
void codegen::multi_def(const ast& node) {
    auto& ids=node[0].child();
    usize size=ids.size();
    if (node[1].type()==ast_tuple) { // (var a,b,c)=(c,b,a);
        auto& vals=node[1].child();
        for(usize i=0;i<size;++i) {
            // check node type, only identifier is allowed
            if (ids[i].type()!=ast_id) {
                die("cannot call identifier in multi-definition", ids[i].location());
                continue;
            }
            calc_gen(vals[i]);
            const string& str=ids[i].str();
            local.empty()?
                gen(op_loadg, global_find(str), ids[i].line()):
                gen(op_loadl, local_find(str), ids[i].line());
        }
    } else { // (var a,b,c)=[0,1,2];
        calc_gen(node[1]);
        for(usize i=0;i<size;++i) {
            // check node type, only identifier is allowed
            if (ids[i].type()!=ast_id) {
                die("cannot call identifier in multi-definition", ids[i].location());
                continue;
            }
            gen(op_callvi, i, node[1].line());
            const string& str=ids[i].str();
            local.empty()?
                gen(op_loadg, global_find(str), ids[i].line()):
                gen(op_loadl, local_find(str), ids[i].line());
        }
        gen(op_pop, 0, node.line());
    }
}

void codegen::def_gen(const ast& node) {
    if (node[0].type()==ast_id && node[1].type()==ast_tuple) {
        die("cannot accept too many values", node[1].location());
    } else if (node[0].type()==ast_multi_id && node[1].type()==ast_tuple && node[0].size()<node[1].size()) {
        die("lack values in multi-definition", node[1].location());
    } else if (node[0].type()==ast_multi_id && node[1].type()==ast_tuple && node[0].size()>node[1].size()) {
        die("too many values in multi-definition", node[1].location());
    }
    node[0].type()==ast_id?single_def(node):multi_def(node);
}

void codegen::multi_assign_gen(const ast& node) {
    if (node[1].type()==ast_tuple && node[0].size()<node[1].size()) {
        die("lack values in multi-assignment", node[1].location());
    } else if (node[1].type()==ast_tuple && node[0].size()>node[1].size()) {
        die("too many values in multi-assignment", node[1].location());
    }
    i32 size=node[0].size();
    if (node[1].type()==ast_tuple) {
        for(i32 i=size-1;i>=0;--i) {
            calc_gen(node[1][i]);
        }
        for(i32 i=0;i<size;++i) {
            mcall(node[0][i]);
            // multi assign user loadl and loadg to avoid meq's stack--
            // and this operation changes local and global value directly
            if (code.back().op==op_mcalll) {
                code.back().op=op_loadl;
            } else if (code.back().op==op_mupval) {
                code.back().op=op_loadu;
            } else if (code.back().op==op_mcallg) {
                code.back().op=op_loadg;
            } else {
                gen(op_meq, 1, node[0][i].line());
            }
        }
    } else {
        calc_gen(node[1]);
        for(i32 i=0;i<size;++i) {
            gen(op_callvi, i, node[1].line());
            // multi assign user loadl and loadg to avoid meq's stack--
            // and this operation changes local and global value directly
            mcall(node[0][i]);
            if (code.back().op==op_mcalll) {
                code.back().op=op_loadl;
            } else if (code.back().op==op_mupval) {
                code.back().op=op_loadu;
            } else if (code.back().op==op_mcallg) {
                code.back().op=op_loadg;
            } else {
                gen(op_meq, 1, node[0][i].line());
            }
        }
        gen(op_pop, 0, node.line());
    }
}

void codegen::cond_gen(const ast& node) {
    std::vector<usize> jmp_label;
    for(auto& tmp:node.child()) {
        if (tmp.type()==ast_if || tmp.type()==ast_elsif) {
            calc_gen(tmp[0]);
            usize ptr=code.size();
            gen(op_jf, 0, tmp.line());
            block_gen(tmp[1]);
            // without 'else' the last condition doesn't need to jmp
            if (&tmp!=&node.child().back()) {
                jmp_label.push_back(code.size());
                gen(op_jmp, 0, tmp.line());
            }
            code[ptr].num=code.size();
        } else {
            block_gen(tmp[0]);
            break;
        }
    }
    for(auto i:jmp_label) {
        code[i].num=code.size();
    }
}

void codegen::loop_gen(const ast& node) {
    continue_ptr.push_front({});
    break_ptr.push_front({});
    switch(node.type()) {
        case ast_while:   while_gen(node);   break;
        case ast_for:     for_gen(node);     break;
        case ast_forindex:forindex_gen(node);break;
        case ast_foreach: foreach_gen(node); break;
    }
}

void codegen::load_continue_break(i32 continue_place,i32 break_place) {
    for(auto i:continue_ptr.front()) {
        code[i].num=continue_place;
    }
    for(auto i:break_ptr.front()) {
        code[i].num=break_place;
    }
    continue_ptr.pop_front();
    break_ptr.pop_front();
}

void codegen::while_gen(const ast& node) {
    usize loop_ptr=code.size();
    calc_gen(node[0]);
    usize condition_ptr=code.size();
    gen(op_jf, 0, node[0].line());

    block_gen(node[1]);
    gen(op_jmp, loop_ptr, node[1].line());
    code[condition_ptr].num=code.size();
    load_continue_break(code.size()-1, code.size());
}

void codegen::for_gen(const ast& node) {
    expr_gen(node[0]);
    usize jmp_place=code.size();
    if (node[1].type()==ast_null) {
        gen(op_pnum, num_table[1], node[1].line());
    } else {
        calc_gen(node[1]);
    }
    usize label_exit=code.size();
    gen(op_jf, 0, node[1].line());

    block_gen(node[3]);
    usize continue_place=code.size();
    expr_gen(node[2]);
    gen(op_jmp, jmp_place, node[2].line());
    code[label_exit].num=code.size();

    load_continue_break(continue_place, code.size());
}

void codegen::expr_gen(const ast& node) {
    switch(node.type()) {
        case ast_null:break;
        case ast_def:def_gen(node);break;
        case ast_multi_assign:multi_assign_gen(node);break;
        case ast_addeq:case ast_subeq:
        case ast_multeq:case ast_diveq:case ast_lnkeq:
        case ast_btandeq:case ast_btoreq:case ast_btxoreq:
            calc_gen(node);
            if (op_addeq<=code.back().op && code.back().op<=op_btxoreq) {
                code.back().num=1;
            } else if (op_addeqc<=code.back().op && code.back().op<=op_lnkeqc) {
                code.back().op=code.back().op-op_addeqc+op_addecp;
            } else {
                gen(op_pop, 0, node.line());
            }
            break;
        case ast_nil:case ast_num:case ast_str:case ast_bool:break;
        case ast_vec:case ast_hash:case ast_func:case ast_call:
        case ast_neg:case ast_lnot:case ast_bnot:
        case ast_bitor:case ast_bitxor:case ast_bitand:
        case ast_add:case ast_sub:case ast_mult:case ast_div:case ast_link:
        case ast_cmpeq:case ast_neq:
        case ast_leq:case ast_less:
        case ast_geq:case ast_grt:
        case ast_or:case ast_and:
        case ast_trino:
            calc_gen(node);
            gen(op_pop, 0, node.line());
            break;
        case ast_equal:
            if (node[0].type()==ast_id) {
                calc_gen(node[1]);
                mcall_id(node[0]);
                // only the first mcall_id can use load
                if (code.back().op==op_mcalll) {
                    code.back().op=op_loadl;
                } else if (code.back().op==op_mupval) {
                    code.back().op=op_loadu;
                } else {
                    code.back().op=op_loadg;
                }
            } else {
                calc_gen(node);
                if (code.back().op==op_meq) {
                    code.back().num=1;
                } else {
                    gen(op_pop, 0, node.line());
                }
            }
            break;
    }
}

void codegen::forindex_gen(const ast& node) {
    calc_gen(node[1]);
    gen(op_cnt, 0, node[1].line());
    usize ptr=code.size();
    gen(op_findex, 0, node.line());
    if (node[0].type()==ast_iter) { // define a new iterator
        const string& str=node[0][0].str();
        local.empty()?
            gen(op_loadg, global_find(str), node[0][0].line()):
            gen(op_loadl, local_find(str), node[0][0].line());
    } else { // use exist variable as the iterator
        mcall(node[0]);
        if (code.back().op==op_mcallg) {
            code.back().op=op_loadg;
        } else if (code.back().op==op_mcalll) {
            code.back().op=op_loadl;
        } else if (code.back().op==op_mupval) {
            code.back().op=op_loadu;
        } else {
            gen(op_meq, 1, node[0].line());
        }
    }
    ++in_iterloop.top();
    block_gen(node[2]);
    --in_iterloop.top();
    gen(op_jmp, ptr, node.line());
    code[ptr].num=code.size();
    load_continue_break(code.size()-1, code.size());
    gen(op_pop, 0, node[1].line());// pop vector
    gen(op_pop, 0, node.line());// pop iterator
}

void codegen::foreach_gen(const ast& node) {
    calc_gen(node[1]);
    gen(op_cnt, 0, node.line());
    usize ptr=code.size();
    gen(op_feach, 0, node.line());
    if (node[0].type()==ast_iter) { // define a new iterator
        const string& str=node[0][0].str();
        local.empty()?
            gen(op_loadg, global_find(str), node[0][0].line()):
            gen(op_loadl, local_find(str), node[0][0].line());
    } else { // use exist variable as the iterator
        mcall(node[0]);
        if (code.back().op==op_mcallg) {
            code.back().op=op_loadg;
        } else if (code.back().op==op_mcalll) {
            code.back().op=op_loadl;
        } else if (code.back().op==op_mupval) {
            code.back().op=op_loadu;
        } else {
            gen(op_meq, 1, node[0].line());
        }
    }
    ++in_iterloop.top();
    block_gen(node[2]);
    --in_iterloop.top();
    gen(op_jmp, ptr, node.line());
    code[ptr].num=code.size();
    load_continue_break(code.size()-1, code.size());
    gen(op_pop, 0, node[1].line());// pop vector
    gen(op_pop, 0, node.line());// pop iterator
}

void codegen::or_gen(const ast& node) {
    calc_gen(node[0]);
    usize l1=code.size();
    gen(op_jt, 0, node[0].line());

    gen(op_pop, 0, node[0].line());
    calc_gen(node[1]);
    usize l2=code.size();
    gen(op_jt, 0, node[1].line());

    gen(op_pop, 0, node[1].line());
    gen(op_pnil, 0, node[1].line());

    code[l1].num=code[l2].num=code.size();
}

void codegen::and_gen(const ast& node) {
    calc_gen(node[0]);
    gen(op_jt, code.size()+2, node[0].line());

    usize lfalse=code.size();
    gen(op_jmp, 0, node[0].line());
    gen(op_pop, 0, node[1].line());// jt jumps here

    calc_gen(node[1]);
    gen(op_jt, code.size()+3, node[1].line());

    code[lfalse].num=code.size();
    gen(op_pop, 0, node[1].line());
    gen(op_pnil, 0, node[1].line());
    // jt jumps here
}

void codegen::trino_gen(const ast& node) {
    calc_gen(node[0]);
    usize lfalse=code.size();
    gen(op_jf, 0, node[0].line());
    calc_gen(node[1]);
    usize lexit=code.size();
    gen(op_jmp, 0, node[1].line());
    code[lfalse].num=code.size();
    calc_gen(node[2]);
    code[lexit].num=code.size();
}

void codegen::calc_gen(const ast& node) {
    switch(node.type()) {
        case ast_nil:  gen(op_pnil,0,node.line());break;
        case ast_num:  num_gen(node);  break;
        case ast_str:  str_gen(node);  break;
        case ast_id:   call_id(node);  break;
        case ast_bool: bool_gen(node); break;
        case ast_vec:  vec_gen(node);  break;
        case ast_hash: hash_gen(node); break;
        case ast_func: func_gen(node); break;
        case ast_call: call_gen(node); break;
        case ast_equal:
            calc_gen(node[1]);
            mcall(node[0]);
            gen(op_meq, 0, node.line());
            break;
        // ast_addeq(22)~ast_lnkeq(26) op_addeq(23)~op_lnkeq(27)
        case ast_addeq:case ast_subeq:case ast_multeq:case ast_diveq:
            if (node[1].type()!=ast_num) {
                calc_gen(node[1]);
            }
            mcall(node[0]);
            if (node[1].type()!=ast_num) {
                gen(node.type()-ast_addeq+op_addeq, 0, node.line());
            } else {
                regist_num(node[1].num());
                gen(node.type()-ast_addeq+op_addeqc, num_table[node[1].num()], node.line());
            }
            break;
        case ast_lnkeq:
            if (node[1].type()!=ast_str) {
                calc_gen(node[1]);
            } else {
                regist_str(node[1].str());
            }
            mcall(node[0]);
            if (node[1].type()!=ast_str) {
                gen(op_lnkeq, 0, node.line());
            } else {
                gen(op_lnkeqc, str_table[node[1].str()], node.line());
            }
            break;
        case ast_btandeq:case ast_btoreq:case ast_btxoreq:
            calc_gen(node[1]);
            mcall(node[0]);
            gen(node.type()-ast_btandeq+op_btandeq, 0, node.line());
            break;
        case ast_or:or_gen(node);break;
        case ast_and:and_gen(node);break;
        // ast_add(33)~ast_link(37) op_add(18)~op_lnk(22)
        case ast_add:case ast_sub:case ast_mult:case ast_div:
            calc_gen(node[0]);
            if (node[1].type()!=ast_num) {
                calc_gen(node[1]);
                gen(node.type()-ast_add+op_add, 0, node.line());
            } else {
                regist_num(node[1].num());
                gen(node.type()-ast_add+op_addc, num_table[node[1].num()], node.line());
            }
            break;
        case ast_link:
            calc_gen(node[0]);
            if (node[1].type()!=ast_str) {
                calc_gen(node[1]);
                gen(op_lnk, 0, node.line());
            } else {
                regist_str(node[1].str());
                gen(op_lnkc, str_table[node[1].str()], node.line());
            }
            break;
        // ast_cmpeq(27)~ast_geq(32) op_eq(29)~op_geq(34)
        case ast_cmpeq:case ast_neq:
            calc_gen(node[0]);
            calc_gen(node[1]);
            gen(node.type()-ast_cmpeq+op_eq, 0, node.line());
            break;
        case ast_less:case ast_leq:case ast_grt:case ast_geq:
            calc_gen(node[0]);
            if (node[1].type()!=ast_num) {
                calc_gen(node[1]);
                gen(node.type()-ast_less+op_less, 0, node.line());
            } else {
                regist_num(node[1].num());
                gen(node.type()-ast_less+op_lessc, num_table[node[1].num()], node.line());
            }
            break;
        case ast_trino:trino_gen(node);break;
        case ast_neg:
            calc_gen(node[0]);
            gen(op_usub, 0, node.line());
            break;
        case ast_lnot:
            calc_gen(node[0]);
            gen(op_lnot, 0, node.line());
            break;
        case ast_bnot:
            calc_gen(node[0]);
            gen(op_bnot, 0, node.line());
            break;
        case ast_bitor:
            calc_gen(node[0]);
            calc_gen(node[1]);
            gen(op_btor, 0, node.line());
            break;
        case ast_bitxor:
            calc_gen(node[0]);
            calc_gen(node[1]);
            gen(op_btxor, 0, node.line());
            break;
        case ast_bitand:
            calc_gen(node[0]);
            calc_gen(node[1]);
            gen(op_btand, 0, node.line());
            break;
        case ast_def:
            single_def(node);
            call_id(node[0]);
            break;
    }
}

void codegen::block_gen(const ast& node) {
    for(auto& tmp:node.child()) {
        switch(tmp.type()) {
            case ast_null:break;
            case ast_id:check_id_exist(tmp);break;
            case ast_nil:case ast_num:case ast_str:case ast_bool:break;
            case ast_file:fileindex=tmp.num();break; // special node type in main block
            case ast_cond:cond_gen(tmp);break;
            case ast_continue:
                continue_ptr.front().push_back(code.size());
                gen(op_jmp, 0, tmp.line());
                break;
            case ast_break:
                break_ptr.front().push_back(code.size());
                gen(op_jmp, 0, tmp.line());
                break;
            case ast_while:
            case ast_for:
            case ast_forindex:
            case ast_foreach:loop_gen(tmp);break;
            case ast_equal:
            case ast_addeq:case ast_subeq:
            case ast_multeq:case ast_diveq:case ast_lnkeq:
            case ast_btandeq:case ast_btoreq:case ast_btxoreq:
            case ast_vec:case ast_hash:case ast_func:case ast_call:
            case ast_neg:case ast_lnot:case ast_bnot:
            case ast_bitor:case ast_bitxor:case ast_bitand:
            case ast_add:case ast_sub:case ast_mult:case ast_div:case ast_link:
            case ast_cmpeq:case ast_neq:
            case ast_leq:case ast_less:
            case ast_geq:case ast_grt:
            case ast_or:
            case ast_and:
            case ast_trino:
            case ast_def:
            case ast_multi_assign:expr_gen(tmp);break;
            case ast_ret:ret_gen(tmp);break;
        }
    }
}

void codegen::ret_gen(const ast& node) {
    for(u32 i=0;i<in_iterloop.top();++i) {
        gen(op_pop, 0, node.line());
        gen(op_pop, 0, node.line());
    }
    if (node.size()) {
        calc_gen(node[0]);
    } else {
        gen(op_pnil, 0, node.line());
    }
    gen(op_ret, 0, node.line());
}

const error& codegen::compile(const parse& parse, const linker& import) {
    fileindex=0;
    file=import.filelist().data();
    in_iterloop.push(0);
    find_symbol(parse.tree()); // search symbols first
    gen(op_intg, global.size(), 0);
    block_gen(parse.tree()); // generate main block
    gen(op_exit, 0, 0);

    // size out of bound check
    if (num_res.size()>0xffffff) {
        err.load(file[0]); // load main execute file
        err.err("code", "too many constant numbers: "+std::to_string(num_res.size()));
    }
    if (str_res.size()>0xffffff) {
        err.load(file[0]); // load main execute file
        err.err("code", "too many constant strings: "+std::to_string(str_res.size()));
    }
    if (global.size()>=STACK_DEPTH) {
        err.load(file[0]); // load main execute file
        err.err("code", "too many global variants: "+std::to_string(global.size()));
    }
    if (code.size()>0xffffff) {
        err.load(file[0]); // load main execute file
        err.err("code", "bytecode size overflow: "+std::to_string(code.size()));
    }
    return err;
}

void codegen::print() {
    // func end stack, reserved for code print
    std::stack<u32> fbstk;
    std::stack<u32> festk;

    // print const numbers
    for(auto& num:num_res) {
        std::cout<<"  .number "<<num<<"\n";
    }

    // print const strings
    for(auto& str:str_res) {
        std::cout<<"  .symbol \""<<rawstr(str)<<"\"\n";
    }

    // print code
    std::cout<<"\n";
    codestream::set(num_res.data(), str_res.data());
    for(u32 i=0;i<code.size();++i) {
        // print opcode index, opcode name, opcode immediate number
        const opcode& c=code[i];
        if (!festk.empty() && i==festk.top()) {
            std::cout<<std::hex<<"<0x"<<fbstk.top()<<std::dec<<">;\n";
            // avoid two empty lines
            if (c.op!=op_newf) {
                std::cout<<"\n";
            }
            fbstk.pop();
            festk.pop();
        }

        // get function begin index and end index
        if (c.op==op_newf) {
            std::cout<<std::hex<<"\nfunc <0x"<<i<<std::dec<<">:\n";
            for(u32 j=i;j<code.size();++j) {
                if (code[j].op==op_jmp) {
                    fbstk.push(i);
                    festk.push(code[j].num);
                    break;
                }
            }
        }

        // output bytecode
        std::cout<<"  "<<codestream(c,i)<<"\n";
    }
}