/**
 * Copyright (c) 2025 Dominic Masters
 * 
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#include "asset.h"
#include "util/memory.h"
#include "util/string.h"
#include "assert/assert.h"
#include "asset/assettype.h"
#include "engine/engine.h"
#include "debug/debug.h"
#include "util/string.h"

errorret_t assetInit(void) {
  memoryZero(&ASSET, sizeof(asset_t));

  #if DOLPHIN
    // Init FAT driver.
    if(!fatInitDefault()) errorThrow("Failed to initialize FAT filesystem.");

    char_t **dolphinSearchPath = (char_t **)ASSET_DOLPHIN_PATHS;
    char_t foundPath[FILENAME_MAX];
    foundPath[0] = '\0';
    do {
      // Try open dir
      DIR *pdir = opendir(*dolphinSearchPath);
      if(pdir == NULL) continue;


      // Scan if file is present
      while(true) {
        struct dirent* pent = readdir(pdir);
        if(pent == NULL) break;

        if(stringCompareInsensitive(pent->d_name, ASSET_FILE) != 0) {
          continue;
        }

        // Copy out filename
        snprintf(
          foundPath,
          FILENAME_MAX,
          "%s/%s",
          *dolphinSearchPath,
          ASSET_FILE
        );
        break;
      }
      
      // Close dir.
      closedir(pdir);

      // Did we find the file here?
      if(foundPath[0] != '\0') break;
    } while(*(++dolphinSearchPath) != NULL);

    if(foundPath[0] != '\0') {
    }

    // Did we find the asset file?
    if(foundPath[0] == '\0') {
      errorThrow("Failed to find asset file on FAT filesystem.");
    }

    ASSET.zip = zip_open(foundPath, ZIP_RDONLY, NULL);
    if(ASSET.zip == NULL) {
      errorThrow("Failed to open asset file on FAT filesystem.");
    }
    errorOk();
  #endif

  // Engine may have been provided the launch path
  if(ENGINE.argc > 0) {
    // Get the directory of the executable
    char_t buffer[FILENAME_MAX];
    stringCopy(buffer, ENGINE.argv[0], FILENAME_MAX);
    size_t len = strlen(buffer);

    // Normalize slashes
    for(size_t i = 0; i < FILENAME_MAX; i++) {
      if(buffer[i] == '\0') break;
      if(buffer[i] == '\\') buffer[i] = '/';
    }

    // Now find the last slash
    char_t *end = buffer + len - 1;
    do {
      end--;
      if(*end == '/') {
        *end = '\0';
        break;
      }
    } while(end != buffer);
    

    // Did we find a slash?
    if(end != buffer) {
      // We found the directory, set as system path
      stringCopy(ASSET.systemPath, buffer, FILENAME_MAX);
    }
  }

  // Default system path, intended to be overridden by the platform
  stringCopy(ASSET.systemPath, ".", FILENAME_MAX);

  // PSP specific asset loading.
  #if PSP
    assertTrue(ENGINE.argc >= 1, "PSP requires launch argument.");

    // PSP is given either the prx OR the PBP file.
    // In the format of "ms0:/PSP/GAME/DUSK/EBOOT.PBP" or "host0:/Dusk.prx"
    // IF the file is the PBP file, we are loading directly on the PSP itself.
    // IF the file is the .prx then we are debugging and fopen will return
    // relative filepaths correctly, e.g. host0:/dusk.dsk will be on host.
    if(
      stringEndsWithCaseInsensitive(ENGINE.argv[0], ".pbp") ||
      ASSET_PBP_READ_PBP_FROM_HOST
    ) {
      const char_t *pbpPath = (
        ASSET_PBP_READ_PBP_FROM_HOST ? "./EBOOT.PBP" : ENGINE.argv[0]
      );
      ASSET.pbpFile = fopen(pbpPath, "rb");
      if(ASSET.pbpFile == NULL) {
        errorThrow("Failed to open PBP file: %s", pbpPath);
      }

      // Get size of PBP file.
      if(fseek(ASSET.pbpFile, 0, SEEK_END) != 0) {
        fclose(ASSET.pbpFile);
        errorThrow("Failed to seek to end of PBP file : %s", pbpPath);
      }
      size_t pbpSize = ftell(ASSET.pbpFile);

      // Rewind to start
      if(fseek(ASSET.pbpFile, 0, SEEK_SET) != 0) {
        fclose(ASSET.pbpFile);
        errorThrow("Failed to seek to start of PBP file : %s", pbpPath);
      }

      // Read the PBP header
      size_t read = fread(
        &ASSET.pbpHeader,
        1,
        sizeof(assetpbp_t),
        ASSET.pbpFile
      );
      if(read != sizeof(assetpbp_t)) {
        fclose(ASSET.pbpFile);
        errorThrow("Failed to read PBP header", pbpPath);
      }
 if(memoryCompare(
        ASSET.pbpHeader.signature,
        ASSET_PBP_SIGNATURE,
        sizeof(ASSET_PBP_SIGNATURE)
      ) != 0) {
        fclose(ASSET.pbpFile);
        errorThrow("Invalid PBP signature in file: %s", pbpPath);
      }

      // If we seek to the PSAR offset, we can read the WAD file from there
      if(fseek(ASSET.pbpFile, ASSET.pbpHeader.psarOffset, SEEK_SET) != 0) {
        fclose(ASSET.pbpFile);
        errorThrow("Failed to seek to PSAR offset in PBP file: %s", pbpPath);
      }

      zip_uint64_t zipPsarOffset = (zip_uint64_t)ASSET.pbpHeader.psarOffset;
      zip_int64_t zipPsarSize = (zip_int64_t)(
        pbpSize - ASSET.pbpHeader.psarOffset
      );

      zip_source_t *psarSource = zip_source_filep_create(
        ASSET.pbpFile,
        zipPsarOffset,
        zipPsarSize,
        NULL
      );
      if(psarSource == NULL) {
        fclose(ASSET.pbpFile);
        errorThrow("Failed to create zip source in PBP file: %s", pbpPath);
      }
      
      ASSET.zip = zip_open_from_source(
        psarSource,
        ZIP_RDONLY,
        NULL
      );
      if(ASSET.zip == NULL) {
        zip_source_free(psarSource);
        fclose(ASSET.pbpFile);
        errorThrow("Failed to open zip from PBP file: %s", pbpPath);
      }

      errorOk();
    }
  #endif

  // Open zip file
  char_t searchPath[FILENAME_MAX];
  const char_t **path = ASSET_SEARCH_PATHS;
  do {
    sprintf(
      searchPath,
      *path,
      ASSET.systemPath,
      ASSET_FILE
    );

    // Try open
    ASSET.zip = zip_open(searchPath, ZIP_RDONLY, NULL);
    if(ASSET.zip == NULL) continue;
    break;// Found!
  } while(*(++path) != NULL);
  
  // Did we open the asset?
  if(ASSET.zip == NULL) errorThrow("Failed to open asset file.");

  errorOk();
}

bool_t assetFileExists(const char_t *filename) {
  assertStrLenMax(filename, FILENAME_MAX, "Filename too long.");

  zip_int64_t idx = zip_name_locate(ASSET.zip, filename, 0);
  if(idx < 0) return false;
  return true;
}

errorret_t assetLoad(const char_t *filename, void *output) {
  assertStrLenMax(filename, FILENAME_MAX, "Filename too long.");
  assertNotNull(output, "Output pointer cannot be NULL.");

  // Determine the asset type by reading the extension
  const assettypedef_t *def = NULL;
  for(uint_fast8_t i = 0; i < ASSET_TYPE_COUNT; i++) {
    const assettypedef_t *cmp = &ASSET_TYPE_DEFINITIONS[i];
    assertNotNull(cmp, "Asset type definition cannot be NULL.");
    if(cmp->extension == NULL) continue;
    if(!stringEndsWithCaseInsensitive(filename, cmp->extension)) continue;
    def = cmp;
    break;
  }
  if(def == NULL) {
    errorThrow("Unknown asset type for file: %s", filename);
  }

  // Get file size of the asset.
  zip_stat_t st;
  zip_stat_init(&st);
  if(!zip_stat(ASSET.zip, filename, 0, &st) == 0) {
    errorThrow("Failed to stat asset file: %s", filename);
  }

  // Minimum file size.
  zip_int64_t fileSize = (zip_int64_t)st.size;
  if(fileSize <= 0) {
    errorThrow("Asset file is empty: %s", filename);
  }

  // Try to open the file
  zip_file_t *file = zip_fopen(ASSET.zip, filename, 0);
  if(file == NULL) {
    errorThrow("Failed to open asset file: %s", filename);
  }

  // Load the asset data
  switch(def->loadStrategy) {
    case ASSET_LOAD_STRAT_ENTIRE:
      assertNotNull(def->entire, "Asset load function cannot be NULL.");

      // Must have more to read
      if(fileSize <= 0) {
        zip_fclose(file);
        errorThrow("No data remaining to read for asset: %s", filename);
      }

      if(fileSize > def->dataSize) {
        zip_fclose(file);
        errorThrow(
          "Asset file has too much data remaining after header: %s",
          filename
        );
      }

      // Create space to read the entire asset data
      void *data = memoryAllocate(fileSize);
      if(!data) {
        zip_fclose(file);
        errorThrow("Failed to allocate memory for asset data of file: %s", filename);
      }

      // Read in the asset data.
      zip_int64_t bytesRead = zip_fread(file, data, fileSize);
      if(bytesRead == 0 || bytesRead > fileSize) {
        memoryFree(data);
        zip_fclose(file);
        errorThrow("Failed to read asset data for file: %s", filename);
      }
      fileSize -= bytesRead;
      
      // Close the file now we have the data
      zip_fclose(file);

      // Pass to the asset type loader
      assetentire_t entire = {
        .data = data,
        .output = output
      };
      errorret_t ret = def->entire(entire);
      memoryFree(data);

      errorChain(ret);
      break;

    case ASSET_LOAD_STRAT_CUSTOM:
      assertNotNull(def->custom, "Asset load function cannot be NULL.");
      assetcustom_t customData = {
        .zipFile = file,
        .output = output
      };
      errorChain(def->custom(customData));
      break;

    default:
      assertUnreachable("Unknown asset load strategy.");
  }

  errorOk();
}

void assetDispose(void) {
  if(ASSET.zip != NULL) {
    zip_close(ASSET.zip);
    ASSET.zip = NULL;
  }

  #if PSP
    if(ASSET.pbpFile != NULL) {
      fclose(ASSET.pbpFile);
      ASSET.pbpFile = NULL;
    }
  #endif
}