#include "../includes/parser.h"
#include <string.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>

#ifndef HIGHMEMORY
#define HIGHMEMORY 65535 //64KiB - 1 AKA 0xFFFF
#endif

//#define HEAPTOP HIGHMEMORY

typedef struct {
    Token* token;
    int address;
} Symbol;

struct intr {
    TokenType struction;
    unsigned int parameter1;
    unsigned int parameter2;
};

Symbol* CreateSymbol(Token* token, int address);
const List* TokensList;
int CurrentToken = 0;
//int HeapTop = HIGHMEMORY;

void AddSymbol(Token*, int);
void PrintSymbols(void);
void HandleOperation(void);
void HandleAssemblerDirective(void);
void AdvanceParser(void);
Token* PeekToken(void);
int ParserAtEnd(void);
int Expect(int, ...);
int ExpectTokenClass(int, ...);
const Symbol* GetSymbol(char*);
List* SymbolsTable;
unsigned int ProgramCounter = 0;

void ParseTokens(List* tokens) {
    if (!tokens) return;

    TokensList = tokens;

    SymbolsTable = CreateList();

    while(!ParserAtEnd()) {
        Token* t = PeekToken();

        switch(t->token_class) {
            case Directive:
                HandleAssemblerDirective();
                break;
            case Opcode:
                ProgramCounter++;
                HandleOperation();
                break;
            case Immediate16:
                ProgramCounter++;
                AddSymbol(t, ProgramCounter);
                break;
            default:
                break;
        }

        AdvanceParser();
    }

    PrintSymbols();
    DestroyList(SymbolsTable);
    printf("Program Counter: %d\n", ProgramCounter);
    //printf("Heap Top: %#06X\n", HeapTop);
}

void HandleAssemblerDirective(void) {

    if (PeekToken()->type == DB) {
        AdvanceParser();

        Token* identifier = PeekToken();

        if (!Expect(1, IDENTIFIER)) {
            fprintf(stderr, "Expected identifier on line %d\n", PeekToken()->line);
            exit(1);
        }

        AddSymbol(identifier, ProgramCounter);

        switch(PeekToken()->type) {
            case STRING:
                ProgramCounter += strlen(PeekToken()->lexeme);

                printf("[INFO] %s = '%s'\n", identifier->lexeme, PeekToken()->lexeme);

                AdvanceParser();

                if (PeekToken()->type == COMMA) {
                    AdvanceParser();

                    if (PeekToken()-> type != NUMBER) {
                        fprintf(stderr, "Expected string termination byte on line %d\n", PeekToken()->line);
                        exit(1);
                    }
                    else {
                        //Add the NULL byte.
                        ProgramCounter++;
                        return;
                    }
                }
            case NUMBER:
                break;
            default:
                fprintf(stderr, "[Line: %d] Expected either a number or string after identifier '%s'.\n", PeekToken()->line, identifier->lexeme);
                exit(1);
        }
    }
}

void HandleOperation(void) {
    const Instruction* inst = GetOpcodeDetails(PeekToken()->type);

    if (!inst) return;

    AdvanceParser();

    printf("[%#05X] %s ", ProgramCounter, inst->lexeme);

    if (inst->parameter_one == None) {
        printf("\n");
        return;
    }

    if (inst->parameter_one && PeekToken()->token_class > 0) {
        //printf("Matched '%s'\n", PeekToken()->lexeme);

        if (inst->parameter_one & Reg) {
            //Encode the register number here.
            printf("%s ", PeekToken()->lexeme);
        }
        else if (inst->parameter_one & Immediate16) {
            if (PeekToken()->type == IDENTIFIER || PeekToken()->type == LABEL) {
                const Symbol* symbol = GetSymbol(PeekToken()->lexeme);

                if (!symbol) {
                    fprintf(stderr, "[Error] %s is undefined.\n", PeekToken()->lexeme);
                    exit(1);
                }

                printf("[%s@%#04X] ", PeekToken()->lexeme, symbol->address);
            }
            else if (PeekToken()->type == NUMBER) printf("%s ", PeekToken()->lexeme);

            ProgramCounter += 2;
        }

        AdvanceParser();
    }

    if (inst->parameter_two == None) { 
        printf("\n");
        return;
    }

    if (PeekToken()->type == COMMA) {
        AdvanceParser();
    } else { 
        fprintf(stderr, "Expected comma at line %d\n", PeekToken()->line);
        exit(666);
        return;
    }

    if (inst->parameter_two && PeekToken()->token_class > 0) {
        //printf("Matched 2 '%s'\n", PeekToken()->lexeme);
        if (inst->parameter_two & Immediate16) {
            if (PeekToken()->type == IDENTIFIER || PeekToken()->type == LABEL) {
                const Symbol* symbol = GetSymbol(PeekToken()->lexeme);

                if (!symbol) {
                    fprintf(stderr, "[Error] %s is undefined.\n", PeekToken()->lexeme);
                    exit(1);
                }

                printf("[%s@%#04X] ", PeekToken()->lexeme, symbol->address);
            }
            else if (PeekToken()->type == NUMBER) printf("%s ", PeekToken()->lexeme);

            ProgramCounter += 2;
        }

        AdvanceParser();
    } else {
        printf("Failed to match %s (class: %d)\n", PeekToken()->lexeme, PeekToken()->token_class);
        printf("Inst %s (class: %x)\n", inst->lexeme, inst->parameter_two);
    }

    printf("\n");
}

int ExpectTokenClass(int count, ...) {
    va_list list;
    Token* token = PeekToken();

    va_start(list, count);

    for(int i = 0; i < count; i++) {
        if (va_arg(list, TokenClass) == token->token_class) {
            va_end(list);
            AdvanceParser();
            return 1;
        }
    }

    va_end(list);

    return 0;
}

int Expect(int count, ...) {
    va_list list;
    Token* token = PeekToken();

    va_start(list, count);

    for(int i = 0; i < count; i++) {
        if (va_arg(list, TokenType) == token->type) {
            va_end(list);
            AdvanceParser();
            return 1;
        }
    }

    va_end(list);

    return 0;
}

void PrintSymbols(void) {
    printf("-----SYMBOLS-----\n");
    for(int i = 0; i < SymbolsTable->size; i++) {
        Symbol* symbol = SymbolsTable->content[i];
        printf("[%#06X] %s\n", symbol->address, symbol->token->lexeme);
    }
    printf("-----SYMBOLS-----\n");
}

void AddSymbol(Token* token, int address) {
    if (!token) return;
    if (token->type != IDENTIFIER && token->type != LABEL) return;

    for(int i = 0; i < SymbolsTable->size; i++) {
        Symbol* s = SymbolsTable->content[i];

        if (strcmp(s->token->lexeme, token->lexeme) == 0) return;
    }

    Symbol* symbol = CreateSymbol(token, address);

    AddListItem(symbol, sizeof(Symbol), SymbolsTable);
}

const Symbol* GetSymbol(char* name) {
    if (!name) return NULL;

    for(int i = 0; i < SymbolsTable->size; i++) {
        const Symbol* s = SymbolsTable->content[i];

        if (strcmp(s->token->lexeme, name) == 0) return s;
    }

    return NULL;
}

Symbol* CreateSymbol(Token* token, int address) {
    Symbol* symbol = calloc(1, sizeof(Symbol));

    if (!symbol) return NULL;

    symbol->token = token;
    symbol->address = address;

    return symbol;
}

void AdvanceParser(void) {
    if (ParserAtEnd()) return;

    CurrentToken++;
}

int ParserAtEnd(void) {
    if (CurrentToken >= TokensList->size) return 1;

    return 0;
}

Token* PeekToken(void) {
    return TokensList->content[CurrentToken];
}