#ifndef LIBCUBESCRIPT_CS_VM_HH
#define LIBCUBESCRIPT_CS_VM_HH

#include "cubescript.hh"

#include <stdlib.h>

#include <ostd/array.hh>
#include <ostd/vector.hh>

namespace cscript {

static constexpr int MaxArguments = 25;
static constexpr int MaxResults = 7;

static constexpr int DummyIdx = MaxArguments;
static constexpr int NumargsIdx = MaxArguments + 1;
static constexpr int DbgaliasIdx = MaxArguments + 2;

enum {
    ID_UNKNOWN = -1, ID_IVAR, ID_FVAR, ID_SVAR, ID_COMMAND, ID_ALIAS,
    ID_LOCAL, ID_DO, ID_DOARGS, ID_IF, ID_RESULT, ID_NOT, ID_AND, ID_OR
};

enum {
    VAL_NULL = 0, VAL_INT, VAL_FLOAT, VAL_STR,
    VAL_ANY, VAL_CODE, VAL_MACRO, VAL_IDENT, VAL_CSTR,
    VAL_CANY, VAL_WORD, VAL_POP, VAL_COND
};

static const int cs_valtypet[] = {
    VAL_NULL, VAL_INT, VAL_FLOAT, VAL_STR,
    VAL_CSTR, VAL_CODE, VAL_MACRO, VAL_IDENT
};

static inline int cs_vtype_to_int(CsValueType v) {
    return cs_valtypet[int(v)];
}

enum {
    CODE_START = 0,
    CODE_OFFSET,
    CODE_NULL, CODE_TRUE, CODE_FALSE, CODE_NOT,
    CODE_POP,
    CODE_ENTER, CODE_ENTER_RESULT,
    CODE_EXIT, CODE_RESULT_ARG,
    CODE_VAL, CODE_VALI,
    CODE_DUP,
    CODE_MACRO,
    CODE_BOOL,
    CODE_BLOCK, CODE_EMPTY,
    CODE_COMPILE, CODE_COND,
    CODE_FORCE,
    CODE_RESULT,
    CODE_IDENT, CODE_IDENTU, CODE_IDENTARG,
    CODE_COM, CODE_COMC, CODE_COMV,
    CODE_CONC, CODE_CONCW, CODE_CONCM, CODE_DOWN,
    CODE_SVAR, CODE_SVARM, CODE_SVAR1,
    CODE_IVAR, CODE_IVAR1, CODE_IVAR2, CODE_IVAR3,
    CODE_FVAR, CODE_FVAR1,
    CODE_LOOKUP, CODE_LOOKUPU, CODE_LOOKUPARG,
    CODE_LOOKUPM, CODE_LOOKUPMU, CODE_LOOKUPMARG,
    CODE_ALIAS, CODE_ALIASU, CODE_ALIASARG,
    CODE_CALL, CODE_CALLU, CODE_CALLARG,
    CODE_PRINT,
    CODE_LOCAL,
    CODE_DO, CODE_DOARGS,
    CODE_JUMP, CODE_JUMP_TRUE, CODE_JUMP_FALSE,
    CODE_JUMP_RESULT_TRUE, CODE_JUMP_RESULT_FALSE,

    CODE_OP_MASK = 0x3F,
    CODE_RET = 6,
    CODE_RET_MASK = 0xC0,

    /* return type flags */
    RET_NULL   = VAL_NULL << CODE_RET,
    RET_STR    = VAL_STR << CODE_RET,
    RET_INT    = VAL_INT << CODE_RET,
    RET_FLOAT  = VAL_FLOAT << CODE_RET,
};

ostd::ConstCharRange cs_debug_line(
    ostd::ConstCharRange p, ostd::ConstCharRange fmt, ostd::CharRange buf
);

void cs_debug_alias(CsState &cs);

template<typename ...A>
void cs_debug_code(CsState &cs, ostd::ConstCharRange fmt, A &&...args) {
    if (cs.nodebug) {
        return;
    }
    cs.get_err().writefln(fmt, ostd::forward<A>(args)...);
    cs_debug_alias(cs);
}

template<typename ...A>
void cs_debug_code_line(
    CsState &cs, ostd::ConstCharRange p, ostd::ConstCharRange fmt, A &&...args
) {
    if (cs.nodebug) {
        return;
    }
    ostd::Array<char, 256> buf;
    cs.get_err().writefln(
        cs_debug_line(p, fmt, ostd::CharRange(buf.data(), buf.size())),
        ostd::forward<A>(args)...
    );
    cs_debug_alias(cs);
}

struct GenState {
    CsState &cs;
    CsVector<ostd::Uint32> code;
    char const *source;

    GenState() = delete;
    GenState(CsState &csr): cs(csr), code(), source(nullptr) {}

    void gen_str(ostd::ConstCharRange word, bool macro = false) {
        if (word.size() <= 3 && !macro) {
            ostd::Uint32 op = CODE_VALI | RET_STR;
            for (ostd::Size i = 0; i < word.size(); ++i) {
                op |= ostd::Uint32(ostd::byte(word[i])) << ((i + 1) * 8);
            }
            code.push(op);
            return;
        }
        code.push(
            (macro ? CODE_MACRO : (CODE_VAL | RET_STR)) | (word.size() << 8)
        );
        code.push_n(
            reinterpret_cast<ostd::Uint32 const *>(word.data()),
            word.size() / sizeof(ostd::Uint32)
        );
        ostd::Size esz = word.size() % sizeof(ostd::Uint32);
        union {
            char c[sizeof(ostd::Uint32)];
            ostd::Uint32 u;
        } end;
        end.u = 0;
        memcpy(end.c, word.data() + word.size() - esz, esz);
        code.push(end.u);
    }

    void gen_str() {
        code.push(CODE_VALI | RET_STR);
    }

    void gen_null() {
        code.push(CODE_VALI | RET_NULL);
    }

    void gen_int(CsInt i = 0) {
        if (i >= -0x800000 && i <= 0x7FFFFF) {
            code.push(CODE_VALI | RET_INT | (i << 8));
        } else {
            code.push(CODE_VAL | RET_INT);
            code.push(i);
        }
    }

    void gen_int(ostd::ConstCharRange word);

    void gen_float(CsFloat f = 0.0f) {
        if (CsInt(f) == f && f >= -0x800000 && f <= 0x7FFFFF) {
            code.push(CODE_VALI | RET_FLOAT | (CsInt(f) << 8));
        } else {
            union {
                CsFloat f;
                ostd::Uint32 u;
            } c;
            c.f = f;
            code.push(CODE_VAL | RET_FLOAT);
            code.push(c.u);
        }
    }

    void gen_float(ostd::ConstCharRange word);

    void gen_ident(CsIdent *id) {
        code.push(
            ((id->get_index() < MaxArguments)
                ? CODE_IDENTARG
                : CODE_IDENT
            ) | (id->get_index() << 8)
        );
    }

    void gen_ident() {
        gen_ident(cs.identmap[DummyIdx]);
    }

    void gen_ident(ostd::ConstCharRange word) {
        gen_ident(cs.new_ident(word));
    }

    void gen_value(
        int wordtype, ostd::ConstCharRange word = ostd::ConstCharRange()
    );

    void gen_main(ostd::ConstCharRange s, int ret_type = VAL_ANY);

    char next_char() {
        return *source++;
    }

    char current() {
        return *source;
    }
};

CsString intstr(int v);
CsString floatstr(CsFloat v);

bool cs_check_num(ostd::ConstCharRange s);

static inline void bcode_incr(ostd::Uint32 *bc) {
    *bc += 0x100;
}

static inline void bcode_decr(ostd::Uint32 *bc) {
    *bc -= 0x100;
    if (ostd::Int32(*bc) < 0x100) {
        delete[] bc;
    }
}

struct CsAliasInternal {
    static void push_arg(
        CsAlias *a, CsValue &v, CsIdentStack &st, bool um = true
    ) {
        if (a->p_astack == &st) {
            /* prevent cycles and unnecessary code elsewhere */
            a->p_val = ostd::move(v);
            clean_code(a);
            return;
        }
        st.val_s = ostd::move(a->p_val);
        st.next = a->p_astack;
        a->p_astack = &st;
        a->p_val = ostd::move(v);
        clean_code(a);
        if (um) {
            a->p_flags &= ~IDF_UNKNOWN;
        }
    }

    static void pop_arg(CsAlias *a) {
        if (!a->p_astack) {
            return;
        }
        CsIdentStack *st = a->p_astack;
        a->p_val = ostd::move(a->p_astack->val_s);
        clean_code(a);
        a->p_astack = st->next;
    }

    static void undo_arg(CsAlias *a, CsIdentStack &st) {
        CsIdentStack *prev = a->p_astack;
        st.val_s = ostd::move(a->p_val);
        st.next = prev;
        a->p_astack = prev->next;
        a->p_val = ostd::move(prev->val_s);
        clean_code(a);
    }

    static void redo_arg(CsAlias *a, CsIdentStack &st) {
        CsIdentStack *prev = st.next;
        prev->val_s = ostd::move(a->p_val);
        a->p_astack = prev;
        a->p_val = ostd::move(st.val_s);
        clean_code(a);
    }

    static void set_arg(CsAlias *a, CsState &cs, CsValue &v) {
        if (cs.p_stack->usedargs & (1 << a->get_index())) {
            a->p_val = ostd::move(v);
            clean_code(a);
        } else {
            push_arg(a, v, cs.p_stack->argstack[a->get_index()], false);
            cs.p_stack->usedargs |= 1 << a->get_index();
        }
    }

    static void set_alias(CsAlias *a, CsState &cs, CsValue &v) {
        a->p_val = ostd::move(v);
        clean_code(a);
        a->p_flags = (a->p_flags & cs.identflags) | cs.identflags;
    }

    static void clean_code(CsAlias *a) {
        ostd::Uint32 *bcode = reinterpret_cast<ostd::Uint32 *>(a->p_acode);
        if (bcode) {
            bcode_decr(bcode);
            a->p_acode = nullptr;
        }
    }

    static CsBytecode *compile_code(CsAlias *a, CsState &cs) {
        if (!a->p_acode) {
            GenState gs(cs);
            gs.code.reserve(64);
            gs.gen_main(a->get_value().get_str());
            ostd::Uint32 *code = new ostd::Uint32[gs.code.size()];
            memcpy(code, gs.code.data(), gs.code.size() * sizeof(ostd::Uint32));
            bcode_incr(code);
            a->p_acode = reinterpret_cast<CsBytecode *>(code);
        }
        return a->p_acode;
    }
};

template<typename F>
static void cs_do_args(CsState &cs, F body) {
    CsIdentStack argstack[MaxArguments];
    int argmask1 = cs.p_stack->usedargs;
    for (int i = 0; argmask1; argmask1 >>= 1, ++i) {
        if (argmask1 & 1) {
            CsAliasInternal::undo_arg(
                static_cast<CsAlias *>(cs.identmap[i]), argstack[i]
            );
        }
    }
    CsIdentLink *prevstack = cs.p_stack->next;
    CsIdentLink aliaslink = {
        cs.p_stack->id, cs.p_stack, prevstack->usedargs, prevstack->argstack
    };
    cs.p_stack = &aliaslink;
    body();
    prevstack->usedargs = aliaslink.usedargs;
    cs.p_stack = aliaslink.next;
    int argmask2 = cs.p_stack->usedargs;
    for (int i = 0; argmask2; argmask2 >>= 1, ++i) {
        if (argmask2 & 1) {
            CsAliasInternal::redo_arg(
                static_cast<CsAlias *>(cs.identmap[i]), argstack[i]
            );
        }
    }
}

CsBytecode *cs_copy_code(CsBytecode *c);

} /* namespace cscript */

#endif /* LIBCUBESCRIPT_CS_VM_HH */