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

#include "tokenizer/File.h"
#include "tokenizer/Tokenizer.h"
#include "utils/Utils.h"

#define TOKEN_BUFFER_LENGTH (1024 * 1024)
#define ERROR_LENGTH 256

static char tokenBuffer[TOKEN_BUFFER_LENGTH];
static int writeIndex = 0;
static int readIndex = 0;
static int16 line = 1;
static char error[ERROR_LENGTH] = {'\0'};

static void tError(const char* format, ...) {
    va_list args;
    va_start(args, format);
    vsnprintf(error, ERROR_LENGTH, format, args);
    va_end(args);
}

static bool tAdd(const void* data, int length) {
    if(writeIndex + length > TOKEN_BUFFER_LENGTH) {
        tError("the token buffer is too small");
        return false;
    }
    memcpy(tokenBuffer + writeIndex, data, length);
    writeIndex += length;
    return true;
}

static bool tAddToken(Token token) {
    unsigned char c = token;
    return tAdd(&c, 1) && tAdd(&line, sizeof(line));
}

static bool tReadTokens(void* dest, int length) {
    if(readIndex + length > writeIndex) {
        return false;
    }
    memcpy(dest, tokenBuffer + readIndex, length);
    readIndex += length;
    return true;
}

static bool tParseLiteral(int c) {
    int index = 1;
    char buffer[64];
    buffer[0] = c;
    while(isLetter(fPeek()) || fPeek() == '.') {
        if(index >= 63) {
            tError("literal is too long");
            return false;
        }
        buffer[index++] = fRead();
    }
    buffer[index] = '\0';
    Token t = tFromName(buffer);
    if(t != T_END) {
        return tAddToken(t);
    }
    return tAddToken(T_LITERAL) && tAdd(buffer, index + 1);
}

static bool tParseNumber(int c) {
    int index = 1;
    char buffer[64];
    buffer[0] = c;
    bool point = false;
    while(true) {
        int c = fPeek();
        if(c == '.') {
            point = true;
        } else if(!isNumber(c)) {
            break;
        } else if(index >= 63) {
            tError("number is too long");
            return false;
        }
        buffer[index++] = fRead();
    }
    buffer[index] = '\0';
    if(point) {
        char* end = NULL;
        float f = strtof(buffer, &end);
        if(end[0] != '\0') {
            tError("invalid float on line %d", line);
            return false;
        }
        return tAddToken(T_CONST_FLOAT) && tAdd(&f, sizeof(float));
    } else {
        char* end = NULL;
        long l = strtol(buffer, &end, 10);
        if(end[0] != '\0' || l > INT_MAX) {
            tError("invalid int on line %d", line);
            return false;
        }
        int i = l;
        return tAddToken(T_CONST_INT) && tAdd(&i, sizeof(int));
    }
}

static bool tAddString() {
    if(!tAddToken(T_TEXT)) {
        return false;
    }
    while(true) {
        int c = fRead();
        if(c == '"') {
            break;
        } else if(c == '\\') {
            switch(fRead()) {
                case '"': c = '"'; break;
                case '\\': c = '\\'; break;
                default:
                    tError("unknown escaped character at line %d", line);
                    return false;
            }
        } else if(c == EOF) {
            tError("unclosed string starting at line %d", line);
            return false;
        }
        if(!tAdd(&c, 1)) {
            return false;
        }
    }
    char c = '\0';
    return tAdd(&c, 1);
}

static bool tAddToken2(Token te, Token t) {
    return fReadIf('=') ? tAddToken(te) : tAddToken(t);
}

static bool tAddToken3(int c, Token tc, Token te, Token t) {
    return fReadIf(c) ? tAddToken(tc) : tAddToken2(te, t);
}

static bool tAddToken4(int c, Token tce, Token tc, Token te, Token t) {
    return fReadIf(c) ? tAddToken2(tce, tc) : tAddToken2(te, t);
}

static bool tLineComment() {
    while(true) {
        int c = fRead();
        if(c == EOF || c == '\n') {
            line++;
            return true;
        }
    }
}

static bool tMultipleLineComment() {
    while(true) {
        int c = fRead();
        if(c == EOF) {
            tError("unclosed comment at line %d", line);
            return false;
        } else if(c == '\n') {
            line++;
        } else if(c == '*' && fReadIf('/')) {
            return true;
        }
    }
}

static bool tSlash() {
    if(fReadIf('/')) {
        return tLineComment();
    } else if(fReadIf('*')) {
        return tMultipleLineComment();
    }
    return tAddToken2(T_DIV_SET, T_DIV);
}

static bool tParseToken() {
    int c = fRead();
    if(c == EOF) {
        return false;
    } else if(isLetter(c)) {
        return tParseLiteral(c);
    } else if(isNumber(c)) {
        return tParseNumber(c);
    }
    switch(c) {
        case ' ': return true;
        case '\n': line++; return true;
        case '+': return tAddToken3('+', T_INCREMENT, T_ADD_SET, T_ADD);
        case '-': return tAddToken3('-', T_DECREMENT, T_SUB_SET, T_SUB);
        case '*': return tAddToken2(T_MUL_SET, T_MUL);
        case '/': return tSlash();
        case '%': return tAddToken2(T_MOD_SET, T_MOD);
        case '<':
            return tAddToken4('<', T_LEFT_SHIFT_SET, T_LEFT_SHIFT, T_LESS_EQUAL,
                              T_LESS);
        case '>':
            return tAddToken4('>', T_RIGHT_SHIFT_SET, T_RIGHT_SHIFT,
                              T_GREATER_EQUAL, T_GREATER);
        case '=': return tAddToken2(T_EQUAL, T_SET);
        case '!': return tAddToken2(T_NOT_EQUAL, T_NOT);
        case '&': return tAddToken3('&', T_AND, T_BIT_AND_SET, T_BIT_AND);
        case '|': return tAddToken3('|', T_OR, T_BIT_OR_SET, T_BIT_OR);
        case '~': return tAddToken(T_BIT_NOT);
        case '^': return tAddToken2(T_BIT_XOR_SET, T_BIT_XOR);
        case ',': return tAddToken(T_COMMA);
        case ';': return tAddToken(T_SEMICOLON);
        case '(': return tAddToken(T_OPEN_BRACKET);
        case ')': return tAddToken(T_CLOSE_BRACKET);
        case '{': return tAddToken(T_OPEN_CURVED_BRACKET);
        case '}': return tAddToken(T_CLOSE_CURVED_BRACKET);
        case '"': return tAddString();
        case '.': return tAddToken(T_POINT);
        case '[': return tAddToken(T_OPEN_SQUARE_BRACKET);
        case ']': return tAddToken(T_CLOSE_SQUARE_BRACKET);
    }
    tError("unknown character on line %d: %c", line, c);
    return false;
}

static void tParseFile() {
    readIndex = 0;
    writeIndex = 0;
    line = 1;
    error[0] = '\0';
    while(tParseToken()) {
    }
}

bool tTokenize(const char* path) {
    if(fOpen(path)) {
        tError("cannot read file '%s'", path);
        return true;
    }
    tParseFile();
    fClose();
    return error[0] != '\0';
}

const char* tGetError() {
    return error;
}

void tResetReader() {
    readIndex = 0;
}

Token tPeekToken() {
    if(readIndex >= writeIndex) {
        return T_END;
    }
    return tokenBuffer[readIndex];
}

Token tReadToken() {
    if(readIndex >= writeIndex) {
        return T_END;
    }
    return tokenBuffer[readIndex++];
}

bool tReadInt(int* i) {
    if(tReadTokens(i, sizeof(int))) {
        return true;
    }
    return false;
}

bool tReadInt16(int16* i) {
    if(tReadTokens(i, sizeof(int16))) {
        return true;
    }
    return false;
}

bool tReadFloat(float* f) {
    if(tReadTokens(f, sizeof(float))) {
        return true;
    }
    return false;
}

const char* tReadString(int* length) {
    *length = 0;
    const char* s = tokenBuffer + readIndex;
    while(readIndex <= writeIndex) {
        (*length)++;
        if(tokenBuffer[readIndex++] == '\0') {
            return s;
        }
    }
    return NULL;
}