#include "lzw.h"
#include "utils.h"
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define READ_BUFFER_SIZE 4096
#define DECOMPRESS_BUFFER_SIZE 4096

uint8_t read_buffer[READ_BUFFER_SIZE], decompress_buffer[DECOMPRESS_BUFFER_SIZE];

int decompress_file(char* filename)
{
    char* outfilename;
    FILE *fp, *outfp;
    int i;
    unsigned int ifnlen, ofnlen;
    struct lzw_ctx* lzw;
    unsigned long int copied_bytes = 0;
    size_t read_available, read_consumed, decompress_consumed;

    lzw = (struct lzw_ctx*)malloc(sizeof(struct lzw_ctx));
    if (lzw == NULL)
        return 0;
    lzw_init(lzw);

    fp = fopen(filename, "rb");
    if (fp == NULL) {
        perror("fopen()");
        return -1;
    }

    ifnlen = strlen(filename);
    ofnlen = ifnlen + 5;
    outfilename = (char*)malloc(ofnlen);
    strlcpy(outfilename, filename, ofnlen);
    for (i = ifnlen - 1; i > 0 && outfilename[i] != '/'; i--)
        if (outfilename[i] == '.') {
            outfilename[i] = '\0';
            break;
        }
    if (strcmp(filename, outfilename) == 0)
        strlcat(outfilename, ".out", ofnlen);

    printf("Writing to %s\n", outfilename);
    outfp = fopen(outfilename, "wb");
    if (outfp == NULL) {
        perror("fopen()");
        free(outfilename);
        return -1;
    }

    read_available = read_consumed = decompress_consumed = 0;
    while (1) {
        if (read_consumed >= read_available) {
            read_available = fread(read_buffer, 1, READ_BUFFER_SIZE, fp);
            read_consumed = 0;
        }
        if (decompress_consumed >= DECOMPRESS_BUFFER_SIZE || ((lzw->eos != 0 || read_available == 0) && decompress_consumed > 0)) {
            fwrite(decompress_buffer, 1, decompress_consumed, outfp);
            copied_bytes += decompress_consumed;
            decompress_consumed = 0;
        }
        if (lzw->eos || read_available == 0)
            break;
        lzw_decompress(lzw, read_buffer, read_available, &read_consumed, decompress_buffer, DECOMPRESS_BUFFER_SIZE, &decompress_consumed);
    }

    free(outfilename);
    fclose(outfp);
    fclose(fp);

    printf("Extracted %lu bytes", copied_bytes);

    return 0;
}

int main(int argc, char* argv[])
{
    int i;

    for (i = 1; i < argc; i++) {
        printf("Decompressing %s\n", argv[i]);
        decompress_file(argv[i]);
    }

    return EXIT_SUCCESS;
}