#include "../includes/opcodes.h"
#include <stdlib.h>
#include <string.h>

#define OPCODECOUNT 15

struct _instruction {
    char* Name;
    Mnemonic Mnemonic;
};

struct _instruction instructions[OPCODECOUNT] = {
    { "add", ADD },//, Reg, Reg | Constant },
    { "sub", SUB },//, Reg, Reg | Constant },
    { "jz", JZ },//, Address, None },
    { "int", INT },//, Constant, None },
    { "yld", YLD },//, None, None },
    { "ret", RET },//, None, None },
    { "cmp", CMP },//, Reg, Reg | Constant },
    { "inc", INC },//, Constant | Reg, None},
    { "dec", DEC },//, None, None},
    { "nop", NOP },//, None, None},
    { "jmp", JMP },//, Address, None},
    { "call", CALL },//, Address, None}
    { "load", LOAD },
    { "je", JE },
    { "loadb", LOADB}
};

Instruction* CreateInstruction(Mnemonic mnemonic) {
    Instruction* instruction = calloc(1, sizeof(Instruction));

    if (!instruction) {
        fprintf(stderr, "Failed to calloc room for an Instruction. %s.\n", strerror(errno));

        return NULL;
    }

    instruction->Mnemonic = mnemonic;
    // instruction->ParameterOne = CreateParameter(NoParameter);
    // instruction->ParameterTwo = CreateParameter(NoParameter);

    return instruction;
}

Parameter* CreateParameter(OpcodeParameter parameterType) {
    Parameter* param = calloc(1, sizeof(Parameter));

    if (!param) {
        fprintf(stderr, "Failed to calloc room for a Parameter. %s,\n", strerror(errno));

        return NULL;
    }

    param->ParameterType = parameterType;

    return param;
}

void FreeInstruction(Instruction* instruction) {
    if (!instruction) return;

    free(instruction);
}

unsigned char GetInstructionMask(Mnemonic type) {
    switch (type) {
        case LOAD:
            return 0x20; //0b00100000; ORing 0x80 marks the first parameter as an address
        case ADD:
            return 0x40;//0b01000000;
        case SUB:
            return 0x60;//0b01100000;
        case CMP:
            return 0x80;//0b10000000;
        case JZ:
            return 0x01;//0b00000001;
        case INT:
            return 0x02; //0b00000010;
        case YLD:
            return 0x03;
        case RET:
            return 0x04;
        case CALL:
            return 0x05;
        case JMP:
            return 0x06;//0b00000110;
        case INC:
            return 0x07;//0b00000111;
        case DEC:
            return 0x08;//0b00001000;
        default:
            return 0x00;
    }
}

void GetMnemonicText(Mnemonic mnemonic, char buffer[12]) {
    memset(buffer, '\0', 12);

    for(int i = 0; i < OPCODECOUNT; i++) {
        if (instructions[i].Mnemonic == mnemonic) { 
            strncpy(buffer, instructions[i].Name, 11);
            break;
        }
    }
}

/*
    NOP  - 0000 0000 NOP
    JZ   - 0000 0001 JZ Address
    INT  - 0000 0010 INT Constant
    YLD  - 0000 0011 YLD
    RET  - 0000 0100 RET
    CALL - 0000 0101 CALL Address
    JMP  - 0000 0110 JMP Address
    IN   - 0000 0111 IN Constant
    OUT  - 0000 1000 OUT Constant
    COPY - 0010 0XXX COPY REG, REG
         - 0010 1XXX COPY REG, Constant    
         - 0011 0XXX COPY REG, Address
         - 1010 0XXX COPY Address, REG
         - 1010 1XXX COPY Address, Constant
         - 1011 0XXX COPY Address, Address
    ADD  - 0100 0XXX ADD REG, REG
         - 0100 1XXX ADD REG, Constant
    SUB  - 0110 0XXX SUB REG, REG
         - 0110 1XXX SUB REG, Constant
    CMP  - 1000 0XXX CMP REG, REG
         - 1000 1XXX CMP REG, Constant
         - 1001 0XXX CMP REG, Address
*/
//COPY      X01X XXXX
//ADD       010X XXXX
//SUB       011X XXXX
//CMP       100X XXXX
//REG       XXX0 0XXX
//Constant  XXX0 1XXX
//Address   XXX1 0XXX
//R1        XXXX X000 -> XXXX X111 (R1 to R8)

// Register registers[REGISTERCOUNT] = {
//     { "r1", R1 },
//     { "r2", R2 },
//     { "r3", R3 },
//     { "r4", R4 },
//     { "r5", R5 },
//     { "r6", R6 },
//     { "r7", R7 },
//     { "r8", R8 }
// };

// const Instruction* GetOpcodeDetails(Mnemonic type) {
//     for(int i = 0; i < OPCODECOUNT; i++) {
//         if (instructions[i].op == type) return &instructions[i];
//     }

//     return NULL;
// }

int IsOpcode(const char* text, Mnemonic* opcode) {
    if (!text) return 0;

    for(int i = 0; i < OPCODECOUNT; i++) {
        if (strcmp(instructions[i].Name, text) == 0) {
            if (opcode) *opcode = instructions[i].Mnemonic;
            return 1;
        }
    }

    return 0;
}

int IsRegister(const char* text, Registers* reg) {
    if (!text) return 0;

    int length = strlen(text);
    Registers r = R8;

    if (length != 2) return 0;
    if (text[0] != 'r') return 0;

    switch(text[1]) {
        case '1':
            r--;
        case '2':
            r--;
        case '3':
            r--;
        case '4':
            r--;
        case '5':
            r--;
        case '6':
            r--;
        case '7':
            r--;
        case '8':
            if (reg) *reg = r;
            return 1;
        default:
            return 0;
    }
}