/*
 * Copyright (C) 2026 Sophie Sitzler
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <https://www.gnu.org/licenses/>.
 */

// @file tpee_ext.h
#pragma once

// @include <tpee.h>
// @desc tpee library handling HTTP communication.
#include <tpee.h>

char *tpee_ext_detect_mime_type(char *filename);
tpee_resp_t tpee_ext_serve_page(char *filename);
tpee_resp_t tpee_ext_serve_file(char *filename);
bool tpee_ext_is_path_match(char *path, char *label);
char *tpee_ext_get_path_var(char *path, char *label, char *key);

#ifdef TPEE_EXT_IMPL

#include <ctype.h>

static int _tpee_ext_read_file(char *filename, char **bytes) {
  FILE *fp = fopen(filename, "rb");
  if (fp == NULL) {
    return -1;
  }
  fseek(fp, 0, SEEK_END);
  long len = ftell(fp);
  fseek(fp, 0, SEEK_SET);
  *bytes = realloc(*bytes, sizeof(char) * len);
  fread(*bytes, len, sizeof(char), fp);
  fclose(fp);
  return len;
}

static char *_tpee_ext_read_text_file(char *filename) {
  FILE *fp = fopen(filename, "r");
  if (fp == NULL) {
    return NULL;
  }
  fseek(fp, 0, SEEK_END);
  long len = ftell(fp);
  fseek(fp, 0, SEEK_SET);
  char *content = malloc(sizeof(char) * (len + 1));
  fread(content, len, sizeof(char), fp);
  content[len] = '\0';
  fclose(fp);
  return content;
}

char *tpee_ext_detect_mime_type(char *filename) {
  int i = strlen(filename);
  for (; i >= 0; i--) {
    if (filename[i] == '.') {
      break;
    }
  }
  char *filename_ext = filename + i + 1;
  if (strcmp(filename_ext, "css") == 0) {
    return "text/css";
  }
  if (strcmp(filename_ext, "js") == 0) {
    return "text/javascript";
  }
  if (strcmp(filename_ext, "png") == 0) {
    return "image/png";
  }
  if (strcmp(filename_ext, "jpg") == 0) {
    return "image/jpg";
  }
  if (strcmp(filename_ext, "json") == 0) {
    return "application/json";
  }
  if (strcmp(filename_ext, "wasm") == 0) {
    return "application/wasm";
  }
  if (strcmp(filename_ext, "svg") == 0) {
    return "image/svg+xml";
  }
  return NULL;
}

tpee_resp_t tpee_ext_serve_page(char *filename) {
  char *html = _tpee_ext_read_text_file(filename);
  tpee_resp_t rsp = tpee_resp_create(TPEE_STATUS_OK);
  tpee_resp_header(&rsp, "Content-Type", "text/html");
  tpee_resp_body(&rsp, html, strlen(html));
  free(html);
  return rsp;
}

tpee_resp_t tpee_ext_serve_file(char *filename) {
  char *bytes = NULL;
  int len = _tpee_ext_read_file(filename, &bytes);
  if (len == -1) {
    return tpee_resp_create(TPEE_STATUS_NOT_FOUND);
  }
  tpee_resp_t resp = tpee_resp_create(TPEE_STATUS_OK);
  char *filetype = tpee_ext_detect_mime_type(filename);
  if (filetype != NULL) {
    tpee_resp_header(&resp, "Content-Type", filetype);
  }
  tpee_resp_body(&resp, bytes, len);
  free(bytes);
  return resp;
}

bool tpee_ext_is_path_match(char *path, char *label) {
  bool is_var = false;
  size_t len = strlen(label);
  size_t var_len = 0;
  size_t idx = 0;
  size_t i = 0;
  size_t path_len = strcspn(path, "?");
  for (; i < path_len; i++) {
    char c = path[i];
    if (!is_var && label[idx] == '{') {
      is_var = true;
      var_len = 0;
    }
    if (is_var) {
      if (!(isalpha(c) || isdigit(c) || c == '-' || c == '_')) {
        is_var = false;
        if (var_len == 0) {
          return false;
        }
        for (; idx < len; idx++) {
          if (label[idx] == '}') {
            idx++;
            break;
          }
        }
        if (c != label[idx]) {
          return false;
        }
        idx++;
      }
      else {
        var_len++;
      }
    }
    else {
      if (c != label[idx]) {
        return false;
      }
      idx++;
    }
  }
  if (is_var) {
    for (; idx < len; idx++) {
      if (label[idx] == '}') {
        idx++;
        break;
      }
    }
    if (var_len == 0) {
      return false;
    }
    is_var = false;
  }
  if (idx != len) {
    return false;
  }
  if (i != path_len) {
    return false;
  }
  return true;
}

char *tpee_ext_get_path_var(char *path, char *label, char *key) {
  bool is_var = false;
  size_t len = strlen(label);
  size_t var_len = 0;
  size_t idx = 0;
  size_t i = 0;
  for (; i < strlen(path); i++) {
    char c = path[i];
    if (!is_var && label[idx] == '{') {
      is_var = true;
      var_len = 0;
    }
    if (is_var) {
      if (!(isalpha(c) || isdigit(c) || c == '-' || c == '_')) {
        is_var = false;
        size_t set = idx + 1;
        for (; idx < len; idx++) {
          if (label[idx] == '}') {
            idx++;
            break;
          }
        }
        if (var_len == 0) {
          return NULL;
        }
        size_t name_len = idx - set - 1;
        char name[name_len + 1];
        memcpy(name, label + set, name_len);
        name[name_len] = '\0';
        if (strcmp(key, name) == 0) {
          char *value = malloc(var_len + 1);
          memcpy(value, path + i - var_len, var_len);
          value[var_len] = '\0';
          return value;
        }
        if (c != label[idx]) {
          return NULL;
        }
        idx++;
      }
      else {
        var_len++;
      }
    }
    else {
      if (c != label[idx]) {
        return NULL;
      }
      idx++;
    }
  }
  if (is_var) {
    size_t set = idx + 1;
    for (; idx < len; idx++) {
      if (label[idx] == '}') {
        idx++;
        break;
      }
    }
    if (var_len == 0) {
      return NULL;
    }
    size_t name_len = idx - set - 1;
    char name[name_len + 1];
    memcpy(name, label + set, name_len);
    name[name_len] = '\0';
    if (strcmp(key, name) == 0) {
      char *value = malloc(var_len + 1);
      memcpy(value, path + i - var_len, var_len);
      value[var_len] = '\0';
      return value;
    }
    is_var = false;
  }
  if (idx != len) {
    return NULL;
  }
  if (i != strlen(path)) {
    return NULL;
  }
  return NULL;
}

#endif /* TPEE_EXT_IMPL */