#include <errno.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

//Import our code
#include "decrypt.h"
#include "fileReader.h"
#include "inflate.h"
#include "utils/min.h"

#define BUFFER_SIZE 512UL * 1024UL //512 KiB
#define ENCRYPTION_HEADER_LENGTH 12UL
#define LOCAL_FILE_HEADER_MAGIC (uint32_t)0x04034b50

uint16_t getUint16(char* buffer) {
  return (uint16_t)buffer[0] | \
    (uint16_t)buffer[1] << 8;
}
uint32_t getUint32(char* buffer) {
  return (uint32_t)buffer[0] | \
    (uint32_t)buffer[1] << 8 | \
    (uint32_t)buffer[2] << 16  | \
    (uint32_t)buffer[3] << 24;
}

int main(int argc, unsigned char *argv[]) {
  if (argc != 4 && argc != 7) {
    fprintf(stderr, "Wrong number of arguments. Usage: patcher-installer <disk_name> <disk_offset> <file_size> [<key0> <key1> <key2>]");
    exit(1);
  }
  //TODO: verify argv and assign it to variables
  char* archiveName = argv[1];
  const unsigned long archiveOffset = atol(argv[2]);
  const unsigned long fileLength = atol(argv[3]);

  const bool isEncrypted = argc == 7;
  if (isEncrypted) {
    uint32_t key0 = atoi(argv[4]);
    uint32_t key1 = atoi(argv[5]);
    uint32_t key2 = atoi(argv[6]);
    //Initialize decryption (pass decryption keys)
    initDecryptor(key0, key1, key2);
  }

  //-------------------------------------------------

  char* compressedChunk = malloc(BUFFER_SIZE);
  if (compressedChunk == NULL) {
    fprintf(stderr, "Could not allocate %lu bytes for compressed buffer.\n", BUFFER_SIZE);
    exit(1);
  }

  char* uncompressedChunk = malloc(BUFFER_SIZE);
  if (uncompressedChunk == NULL) {
    fprintf(stderr, "Could not allocate %lu bytes for uncompressed buffer.\n", BUFFER_SIZE);
    exit(1);
  }

  //-------------------------------------------------

  //Initialize file reader
  initFileReader(archiveName, archiveOffset);

  //Skip local file header (30 bytes + additional length)
  getBytes(compressedChunk, 30UL);
  //Check that header is correct
  const uint32_t magic = getUint32(compressedChunk);
  if (magic != LOCAL_FILE_HEADER_MAGIC) {
    fprintf(stderr, "Wrong magic in local file header, expected %#010x but found %#010x.", LOCAL_FILE_HEADER_MAGIC, magic);
    exit(1);
  }
  //Read additional length
  const unsigned long additionalLength = getUint16(compressedChunk + 26) + getUint16(compressedChunk + 28);
  getBytes(compressedChunk, additionalLength);

  //If file is encrypted, skip 12-byte encryption header
  if (isEncrypted) {
    getBytes(compressedChunk, ENCRYPTION_HEADER_LENGTH);
    decrypt(compressedChunk, ENCRYPTION_HEADER_LENGTH);
  }

  //-------------------------------------------------

  struct InflateOutput inflateResult;
  inflateInit(compressedChunk, uncompressedChunk, BUFFER_SIZE);

  //Read actual file
  unsigned long remainingBytes = fileLength;
  bool needToRead = true;
  unsigned long chunkSize;
  while (remainingBytes > 0) {
    if (needToRead) {
      chunkSize = min(BUFFER_SIZE, remainingBytes);
      getBytes(compressedChunk, chunkSize);
      remainingBytes -= chunkSize;

      //Decrypt file if it is encrypted
      if (isEncrypted) {
        //TODO: For highest performance, we need to move if condition outside of while loop
        decrypt(compressedChunk, chunkSize);
      }
    }

    //Decompress file
    //bytes are contained in uncompressedChunk from [0, inflateResult.numBytesWrittenToOutput - 1]
    inflateResult = inflateInflate(needToRead ? chunkSize : 0, remainingBytes > 0);
    needToRead = inflateResult.needMoreInput;

    write(1, uncompressedChunk, inflateResult.numBytesWrittenToOutput);

    //Optionally perform xdelta3
    //TODO

  }

  //release memory
  free(compressedChunk);
  free(uncompressedChunk);

  return 0;
}