#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "Operation.h"
#include "Script.h"

static void sError(Script* sc, const char* format, ...) {
    va_list args;
    va_start(args, format);
    vsnprintf(sc->error, SCRIPT_ERROR_SIZE, format, args);
    va_end(args);
}

static bool sPrinter(Object* o) {
    switch(o->type) {
        case OT_INT: printf("%d\n", o->data.intValue); return false;
        case OT_FLOAT: printf("%.2f\n", o->data.floatValue); return false;
        case OT_NULL: printf("null\n"); return false;
        case OT_BOOL: printf(o->data.intValue ? "true\n" : "false\n"); return false;
        case OT_VOID: printf("void\n"); return false;
    }
    return true;
}

static ObjectPrinter printer = sPrinter;

static bool sRead(Script* sc, void* buffer, int length) {
    if(sc->readIndex + length > sc->code->length) {
        sError(sc, "cannot read expected %d bytes of data from bytecode on line %d", sc->line);
        return true;
    }
    memcpy(buffer, sc->code->code + sc->readIndex, length);
    sc->readIndex += length;
    return false;
}

static Operation sReadOperation(Script* sc) {
    unsigned char c;
    if(sRead(sc, &c, 1)) {
        return OP_NOTHING;
    }
    return c;
}

static bool sReadInt(Script* sc, int* i) {
    return !sRead(sc, i, sizeof(int));
}

static bool sCheckType(Script* sc, Object* o, ObjectType ot) {
    if(o->type == ot) {
        return true;
    }
    sError(sc, "object is not of type %s on line %d", oGetName(ot), sc->line);
    return false;
}

static bool sPush(Script* sc, Object* o) {
    if(sc->stackIndex >= SCRIPT_STACK_SIZE) {
        sError(sc, "stack overflow on line %d", sc->line);
        return false;
    }
    sc->stack[sc->stackIndex++] = *o;
    return true;
}

static bool sPop(Script* sc, Object* o) {
    if(sc->stackIndex <= 0) {
        sError(sc, "stack underflow on line %d", sc->line);
        return true;
    }
    *o = sc->stack[--sc->stackIndex];
    return false;
}

static void sPopEmpty(Script* sc) {
    Object o;
    sPop(sc, &o);
}

static Object* sPeek(Script* sc) {
    if(sc->stackIndex <= 0) {
        sError(sc, "stack underflow on line %d", sc->line);
        return NULL;
    }
    return sc->stack + (sc->stackIndex - 1);
}

static bool sPushInt(Script* sc, int value) {
    Object o = {.type = OT_INT, .data.intValue = value};
    return sPush(sc, &o);
}

static void sPushFloat(Script* sc, float value) {
    Object o = {.type = OT_FLOAT, .data.floatValue = value};
    sPush(sc, &o);
}

static void sPushNull(Script* sc) {
    Object o = {.type = OT_NULL};
    sPush(sc, &o);
}

static void sPushBool(Script* sc, bool value) {
    Object o = {.type = OT_BOOL, .data.intValue = value};
    sPush(sc, &o);
}

static void sPushVars(Script* sc) {
    int vars = 0;
    int offset = 0;
    if(sReadInt(sc, &vars) && sReadInt(sc, &offset)) {
        int stackVarIndex = sc->stackVarIndex;
        sc->stackVarIndex = sc->stackIndex - offset;
        for(int i = 0; i < vars - offset; i++) {
            sPushNull(sc);
        }
        sPushInt(sc, stackVarIndex);
    }
}

static void sPopVars(Script* sc) {
    int value = 0;
    Object o;
    if(sReadInt(sc, &value) && !sPop(sc, &o) && sCheckType(sc, &o, OT_INT)) {
        sc->stackVarIndex = o.data.intValue;
        if(sc->stackIndex < value) {
            sError(sc, "stack underflow on line %d", sc->line);
        } else {
            sc->stackIndex -= value;
        }
    }
}

static void sSet(Script* sc) {
    int value = 0;
    if(sReadInt(sc, &value)) {
        sPop(sc, sc->stack + value + sc->stackVarIndex);
    }
}

static void sGet(Script* sc) {
    int value = 0;
    if(sReadInt(sc, &value)) {
        sPush(sc, sc->stack + value + sc->stackVarIndex);
    }
}

static void sPreIncrement(Script* sc) {
    int value = 0;
    if(sReadInt(sc, &value)) {
        Object* o = sc->stack + value + sc->stackVarIndex;
        if(o->type == OT_INT) {
            o->data.intValue++;
        } else if(o->type == OT_FLOAT) {
            o->data.floatValue++;
        } else {
            sError(sc, "variable is not a number on line %d", sc->line);
            return;
        }
        sPush(sc, o);
    }
}

static void sPostIncrement(Script* sc) {
    int value = 0;
    if(sReadInt(sc, &value)) {
        Object* o = sc->stack + value + sc->stackVarIndex;
        if(o->type == OT_INT) {
            sPush(sc, o);
            o->data.intValue++;
        } else if(o->type == OT_FLOAT) {
            sPush(sc, o);
            o->data.floatValue++;
        } else {
            sError(sc, "variable is not a number on line %d", sc->line);
        }
    }
}

static void sPreDecrement(Script* sc) {
    int value = 0;
    if(sReadInt(sc, &value)) {
        Object* o = sc->stack + value + sc->stackVarIndex;
        if(o->type == OT_INT) {
            o->data.intValue--;
        } else if(o->type == OT_FLOAT) {
            o->data.floatValue--;
        } else {
            sError(sc, "variable is not a number on line %d", sc->line);
            return;
        }
        sPush(sc, o);
    }
}

static void sPostDecrement(Script* sc) {
    int value = 0;
    if(sReadInt(sc, &value)) {
        Object* o = sc->stack + value + sc->stackVarIndex;
        if(o->type == OT_INT) {
            sPush(sc, o);
            o->data.intValue--;
        } else if(o->type == OT_FLOAT) {
            sPush(sc, o);
            o->data.floatValue--;
        } else {
            sError(sc, "variable is not a number on line %d", sc->line);
        }
    }
}

static void sPushCodeInt(Script* sc) {
    int value = 0;
    if(sReadInt(sc, &value)) {
        sPushInt(sc, value);
    }
}

static void sPushCodeFloat(Script* sc) {
    float value = 0;
    if(sRead(sc, &value, sizeof(float))) {
        sError(sc, "cannot read a float from the bytecode on line %d", sc->line);
        return;
    }
    sPushFloat(sc, value);
}

static void sNumberBinary(Script* sc, int (*fInt)(Script*, int, int), float (*fFloat)(float, float)) {
    Object o[2];
    if(sPop(sc, o) || sPop(sc, o + 1)) {
        return;
    } else if(o[0].type == OT_INT && o[1].type == OT_INT) {
        sPushInt(sc, fInt(sc, o[0].data.intValue, o[1].data.intValue));
    } else if(o[0].type == OT_FLOAT && o[1].type == OT_INT) {
        sPushFloat(sc, fFloat(o[0].data.floatValue, o[1].data.intValue));
    } else if(o[0].type == OT_INT && o[1].type == OT_FLOAT) {
        sPushFloat(sc, fFloat(o[0].data.intValue, o[1].data.floatValue));
    } else if(o[0].type == OT_FLOAT && o[1].type == OT_FLOAT) {
        sPushFloat(sc, fFloat(o[0].data.floatValue, o[1].data.floatValue));
    } else {
        sError(sc, "object is not a number on line %d", sc->line);
    }
}

static void sIntBinary(Script* sc, int (*f)(Script*, int, int)) {
    Object o[2];
    if(!sPop(sc, o) && !sPop(sc, o + 1) && sCheckType(sc, o, OT_INT) && sCheckType(sc, o + 1, OT_INT)) {
        sPushInt(sc, f(sc, o[0].data.intValue, o[1].data.intValue));
    }
}

static int sIntAdd(Script* sc, int a, int b) {
    (void)sc;
    return a + b;
}

static int sIntSub(Script* sc, int a, int b) {
    (void)sc;
    return b - a;
}

static int sIntMul(Script* sc, int a, int b) {
    (void)sc;
    return a * b;
}

static int sIntDiv(Script* sc, int a, int b) {
    if(a == 0) {
        sError(sc, "division by 0 on line %d", sc->line);
        return b;
    }
    return b / a;
}

static int sMod(Script* sc, int a, int b) {
    if(a == 0) {
        sError(sc, "module of 0 on line %d", sc->line);
        return b;
    }
    return b % a;
}

static float sFloatAdd(float a, float b) {
    return a + b;
}

static float sFloatSub(float a, float b) {
    return b - a;
}

static float sFloatMul(float a, float b) {
    return a * b;
}

static float sFloatDiv(float a, float b) {
    return b / a;
}

static void sBoolBinary(Script* sc, bool (*fInt)(int, int), bool (*fFloat)(float, float)) {
    Object o[2];
    if(sPop(sc, o) || sPop(sc, o + 1)) {
        return;
    } else if(o[0].type == OT_INT && o[1].type == OT_INT) {
        sPushBool(sc, fInt(o[0].data.intValue, o[1].data.intValue));
    } else if(o[0].type == OT_FLOAT && o[1].type == OT_INT) {
        sPushBool(sc, fFloat(o[0].data.floatValue, o[1].data.intValue));
    } else if(o[0].type == OT_INT && o[1].type == OT_FLOAT) {
        sPushBool(sc, fFloat(o[0].data.intValue, o[1].data.floatValue));
    } else if(o[0].type == OT_FLOAT && o[1].type == OT_FLOAT) {
        sPushBool(sc, fFloat(o[0].data.floatValue, o[1].data.floatValue));
    } else {
        sError(sc, "object is not a number on line %d", sc->line);
    }
}

static bool sIntLess(int a, int b) {
    return b < a;
}

static bool sIntGreater(int a, int b) {
    return b > a;
}

static bool sFloatLess(float a, float b) {
    return b < a;
}

static bool sFloatGreater(float a, float b) {
    return b > a;
}

static void sInvertSign(Script* sc) {
    Object* o = sPeek(sc);
    if(o == NULL) {
        return;
    } else if(o->type == OT_INT) {
        o->data.intValue = -o->data.intValue;
    } else if(o->type == OT_FLOAT) {
        o->data.floatValue = -o->data.floatValue;
    } else {
        sError(sc, "object is not a number on line %d", sc->line);
    }
}

static void sEqual(Script* sc) {
    Object o[2];
    if(sPop(sc, o) || sPop(sc, o + 1)) {
        return;
    } else if(o[0].type == OT_INT && o[1].type == OT_INT) {
        sPushBool(sc, o[0].data.intValue == o[1].data.intValue);
    } else if(o[0].type == OT_INT && o[1].type == OT_FLOAT) {
        sPushBool(sc, o[0].data.intValue == o[1].data.floatValue);
    } else if(o[0].type == OT_FLOAT && o[1].type == OT_INT) {
        sPushBool(sc, o[0].data.floatValue == o[1].data.intValue);
    } else if(o[0].type == OT_FLOAT && o[1].type == OT_FLOAT) {
        sPushBool(sc, o[0].data.floatValue == o[1].data.floatValue);
    } else if(o[0].type == OT_BOOL && o[1].type == OT_BOOL) {
        sPushBool(sc, o[0].data.intValue == o[1].data.intValue);
    } else if(o[0].type == OT_NULL && o[1].type == OT_NULL) {
        sPushBool(sc, true);
    } else {
        sError(sc, "object types do not match on line %d", sc->line);
    }
}

static void sNot(Script* sc) {
    Object* o = sPeek(sc);
    if(o != NULL && sCheckType(sc, o, OT_BOOL)) {
        o->data.intValue = !o->data.intValue;
    }
}

static void sAnd(Script* sc) {
    Object o[2];
    if(!sPop(sc, o) && !sPop(sc, o + 1) && sCheckType(sc, o, OT_BOOL) && sCheckType(sc, o + 1, OT_BOOL)) {
        sPushBool(sc, o[0].data.intValue && o[1].data.intValue);
    }
}

static void sOr(Script* sc) {
    Object o[2];
    if(!sPop(sc, o) && !sPop(sc, o + 1) && sCheckType(sc, o, OT_BOOL) && sCheckType(sc, o + 1, OT_BOOL)) {
        sPushBool(sc, o[0].data.intValue || o[1].data.intValue);
    }
}

static void sPrint(Script* sc) {
    Object o;
    if(!sPop(sc, &o) && printer(&o)) {
        sError(sc, "cannot print given object on line %d", sc->line);
    }
}

static void sLine(Script* sc) {
    if(sRead(sc, &sc->line, 2)) {
        sError(sc, "line operation without a line near line %d", sc->line);
    }
}

static void sGoTo(Script* sc) {
    int gotoIndex;
    if(sReadInt(sc, &gotoIndex)) {
        sc->readIndex = gotoIndex;
    }
}

static void sGoSub(Script* sc) {
    int gotoIndex;
    int arguments;
    if(sReadInt(sc, &gotoIndex) && sReadInt(sc, &arguments)) {
        int returnStackIndex = sc->stackIndex - arguments - 1;
        if(returnStackIndex < 0 || sc->stack[returnStackIndex].type != OT_INT) {
            sError(sc, "cannot find return address entry on stack on line %d", sc->line);
            return;
        }
        sc->stack[returnStackIndex].data.intValue = sc->readIndex;
        sc->readIndex = gotoIndex;
    }
}

static void sIfGoTo(Script* sc) {
    int gotoIndex;
    Object o;
    if(sReadInt(sc, &gotoIndex) && !sPop(sc, &o) && sCheckType(sc, &o, OT_BOOL) && !o.data.intValue) {
        sc->readIndex = gotoIndex;
    }
}

static void sSetReturn(Script* sc) {
    sPop(sc, &sc->returnValue);
}

static void sReturn(Script* sc) {
    Object o;
    if(!sPop(sc, &o) && sCheckType(sc, &o, OT_INT)) {
        sc->readIndex = o.data.intValue;
        if(sc->returnValue.type != OT_VOID) {
            sPush(sc, &sc->returnValue);
            sc->returnValue.type = OT_VOID;
        }
    }
}

static void sDuplicate(Script* sc) {
    Object* o = sPeek(sc);
    if(o != NULL) {
        sPush(sc, o);
    }
}

static void sConsumeInstruction(Script* sc) {
    switch(sReadOperation(sc)) {
        case OP_NOTHING: break;
        case OP_PUSH_INT: sPushCodeInt(sc); break;
        case OP_PUSH_FLOAT: sPushCodeFloat(sc); break;
        case OP_PUSH_NULL: sPushNull(sc); break;
        case OP_PUSH_TRUE: sPushBool(sc, true); break;
        case OP_PUSH_FALSE: sPushBool(sc, false); break;
        case OP_PUSH_VARS: sPushVars(sc); break;
        case OP_POP_VARS: sPopVars(sc); break;
        case OP_POP: sPopEmpty(sc); break;
        case OP_SET: sSet(sc); break;
        case OP_GET: sGet(sc); break;
        case OP_PRE_INCREMENT: sPreIncrement(sc); break;
        case OP_POST_INCREMENT: sPostIncrement(sc); break;
        case OP_PRE_DECREMENT: sPreDecrement(sc); break;
        case OP_POST_DECREMENT: sPostDecrement(sc); break;
        case OP_ADD: sNumberBinary(sc, sIntAdd, sFloatAdd); break;
        case OP_SUB: sNumberBinary(sc, sIntSub, sFloatSub); break;
        case OP_MUL: sNumberBinary(sc, sIntMul, sFloatMul); break;
        case OP_DIV: sNumberBinary(sc, sIntDiv, sFloatDiv); break;
        case OP_MOD: sIntBinary(sc, sMod); break;
        case OP_INVERT_SIGN: sInvertSign(sc); break;
        case OP_LESS: sBoolBinary(sc, sIntLess, sFloatLess); break;
        case OP_GREATER: sBoolBinary(sc, sIntGreater, sFloatGreater); break;
        case OP_EQUAL: sEqual(sc); break;
        case OP_NOT: sNot(sc); break;
        case OP_AND: sAnd(sc); break;
        case OP_OR: sOr(sc); break;
        case OP_PRINT: sPrint(sc); break;
        case OP_LINE: sLine(sc); break;
        case OP_GOTO: sGoTo(sc); break;
        case OP_GOSUB: sGoSub(sc); break;
        case OP_IF_GOTO: sIfGoTo(sc); break;
        case OP_SET_RETURN: sSetReturn(sc); break;
        case OP_RETURN: sReturn(sc); break;
        case OP_DUPLICATE: sDuplicate(sc); break;
    }
}

static bool sHasData(Script* sc) {
    return sc->readIndex < sc->code->length;
}

Script* sInit(ByteCode* code) {
    Script* sc = malloc(sizeof(Script));
    sc->error[0] = '\0';
    sc->code = code;
    sc->readIndex = 0;
    sc->returnValue.type = OT_VOID;
    sc->stackIndex = 0;
    sc->stackVarIndex = 0;
    sc->line = 0;
    return sc;
}

void sDelete(Script* sc) {
    bcDelete(sc->code);
    free(sc);
}

void sRun(Script* sc) {
    while(sHasData(sc)) {
        sConsumeInstruction(sc);
        if(sc->error[0] != '\0') {
            puts(sc->error);
            return;
        }
    }
}

void sSetPrinter(ObjectPrinter p) {
    printer = p;
}

static void sPrintInt(Script* sc, const char* msg) {
    int value = 0;
    sReadInt(sc, &value);
    printf("%s %d\n", msg, value);
}

static void sPrint2Int(Script* sc, const char* msg) {
    int a = 0;
    sReadInt(sc, &a);
    int b = 0;
    sReadInt(sc, &b);
    printf("%s %d %d\n", msg, a, b);
}

static void sPrintInt16(Script* sc, const char* msg) {
    int value = 0;
    sRead(sc, &value, 2);
    printf("%s %d\n", msg, value);
}

static void sPrintFloat(Script* sc, const char* msg) {
    float value = 0;
    sRead(sc, &value, sizeof(float));
    printf("%s %.2f\n", msg, value);
}

void sPrintCode(Script* sc) {
    int oldRead = sc->readIndex;
    sc->readIndex = 0;
    while(sHasData(sc)) {
        printf(" %3d | ", sc->readIndex);
        switch(sReadOperation(sc)) {
            case OP_NOTHING: puts("Nothing"); break;
            case OP_PUSH_INT: sPrintInt(sc, "Push Int"); break;
            case OP_PUSH_FLOAT: sPrintFloat(sc, "Push Float"); break;
            case OP_PUSH_NULL: puts("Push null"); break;
            case OP_PUSH_TRUE: puts("Push true"); break;
            case OP_PUSH_FALSE: puts("Push false"); break;
            case OP_PUSH_VARS: sPrint2Int(sc, "Push Vars"); break;
            case OP_POP_VARS: sPrintInt(sc, "Pop Vars"); break;
            case OP_POP: puts("Pop"); break;
            case OP_SET: sPrintInt(sc, "Set"); break;
            case OP_GET: sPrintInt(sc, "Get"); break;
            case OP_PRE_INCREMENT: sPrintInt(sc, "Pre Increment"); break;
            case OP_POST_INCREMENT: sPrintInt(sc, "Post Increment"); break;
            case OP_PRE_DECREMENT: sPrintInt(sc, "Pre Decrement"); break;
            case OP_POST_DECREMENT: sPrintInt(sc, "Post Decrement"); break;
            case OP_ADD: puts("Add"); break;
            case OP_SUB: puts("Sub"); break;
            case OP_MUL: puts("Mul"); break;
            case OP_DIV: puts("Div"); break;
            case OP_MOD: puts("Mod"); break;
            case OP_INVERT_SIGN: puts("Invert Sign"); break;
            case OP_LESS: puts("Less"); break;
            case OP_GREATER: puts("Greater"); break;
            case OP_EQUAL: puts("Equal"); break;
            case OP_NOT: puts("Not"); break;
            case OP_AND: puts("And"); break;
            case OP_OR: puts("And"); break;
            case OP_PRINT: puts("Print"); break;
            case OP_LINE: sPrintInt16(sc, "------------ Line"); break;
            case OP_GOTO: sPrintInt(sc, "GoTo"); break;
            case OP_GOSUB: sPrint2Int(sc, "GoSub"); break;
            case OP_IF_GOTO: sPrintInt(sc, "If GoTo"); break;
            case OP_SET_RETURN: puts("Set Return"); break;
            case OP_RETURN: puts("Return"); break;
            case OP_DUPLICATE: puts("Duplicate"); break;
        }
    }
    sc->readIndex = oldRead;
}