#include "../beaker.h"        
#include "beaker_globals.h"   
#include <stdio.h>            
#include <stdlib.h>           
#include <string.h>           
#include <sys/socket.h>       
#include <sys/stat.h>         
#include <unistd.h>           
#include <errno.h>

void set_handler(const char *path, RequestHandler handler) {

  if (handler_count < MAX_HANDLERS) {

    strncpy(handlers[handler_count].path, path, MAX_PATH_LEN - 1);
    handlers[handler_count].path[MAX_PATH_LEN - 1] = '\0';

    handlers[handler_count].handler = handler;

    handler_count++;
  } else {

    fprintf(stderr,
            "[WARNING] set_handler: Maximum number of handlers reached. Cannot register handler for '%s'.\n",
            path);
  }
}

const char *get_mime_type(const char *file_path) {

  const char *ext = strrchr(file_path, '.');
  if (!ext) {
    return "application/octet-stream"; 
  }
  ext++; 

  if (strcmp(ext, "html") == 0 || strcmp(ext, "htm") == 0)
    return "text/html";
  if (strcmp(ext, "css") == 0)
    return "text/css";
  if (strcmp(ext, "js") == 0)
    return "application/javascript";
  if (strcmp(ext, "json") == 0)
    return "application/json";
  if (strcmp(ext, "jpg") == 0 || strcmp(ext, "jpeg") == 0)
    return "image/jpeg";
  if (strcmp(ext, "png") == 0)
    return "image/png";
  if (strcmp(ext, "gif") == 0)
    return "image/gif";
  if (strcmp(ext, "ico") == 0)
    return "image/x-icon";
  if (strcmp(ext, "svg") == 0)
    return "image/svg+xml";
  if (strcmp(ext, "pdf") == 0)
    return "application/pdf";
  if (strcmp(ext, "txt") == 0)
    return "text/plain";

  return "application/octet-stream";
}

static int canonicalize_path(char *canonical, const char *path, size_t max_len) {
    char components[MAX_URL_PARAMS][MAX_KEY_LEN];
    int component_count = 0;

    char *path_copy = strdup(path);
    if (!path_copy) {
        return -1;
    }

    char *token = strtok(path_copy, "/");
    while (token) {
        if (strcmp(token, ".") == 0) {

        } else if (strcmp(token, "..") == 0) {

            if (component_count > 0) {
                component_count--;
            } else {

                fprintf(stderr, "[SECURITY] Path traversal attempt: %s\n", path);
                free(path_copy);
                return -1;
            }
        } else if (strlen(token) > 0) {

            if (component_count < MAX_URL_PARAMS) {
                strncpy(components[component_count], token, MAX_KEY_LEN - 1);
                components[component_count][MAX_KEY_LEN - 1] = '\0';
                component_count++;
            }
        }
        token = strtok(NULL, "/");
    }

    free(path_copy);

    canonical[0] = '\0';
    for (int i = 0; i < component_count; i++) {
        if (strlen(canonical) + strlen(components[i]) + 2 > max_len) {
            fprintf(stderr, "[ERROR] Canonical path too long\n");
            return -1;
        }
        strcat(canonical, "/");
        strcat(canonical, components[i]);
    }

    if (canonical[0] == '\0') {
        strcpy(canonical, "/");
    }

    return 0;
}

static bool is_safe_path_component(const char *component) {

    if (strstr(component, "..") ||
        strstr(component, "//") ||
        strchr(component, '\0') != component + strlen(component)) {
        return false;
    }

    for (size_t i = 0; component[i]; i++) {
        if (component[i] < 32 && component[i] != '\t') {
            return false;
        }
    }

    return true;
}

static int url_decode(char *dst, const char *src, size_t dst_size) {
    size_t i = 0, j = 0;

    while (src[i] && j < dst_size - 1) {
        if (src[i] == '%') {

            if (src[i+1] && src[i+2]) {
                char hex[3] = {src[i+1], src[i+2], '\0'};
                char *endptr;
                long value = strtol(hex, &endptr, 16);

                if (*endptr != '\0') {
                    fprintf(stderr, "[SECURITY] Invalid URL encoding: %%%s\n", hex);
                    return -1;
                }

                if (value == 0) {
                    fprintf(stderr, "[SECURITY] Null byte in URL encoding\n");
                    return -1;
                }

                dst[j++] = (char)value;
                i += 3;
            } else {
                fprintf(stderr, "[SECURITY] Incomplete URL encoding at end\n");
                return -1;
            }
        } else if (src[i] == '+') {

            dst[j++] = ' ';
            i++;
        } else {
            dst[j++] = src[i++];
        }
    }

    dst[j] = '\0';
    return 0;
}

char *parse_request_url(const char *request_line, UrlParams *params) {
    char method[16];
    char raw_url_full[MAX_PATH_LEN];
    char http_version[16];

    if (sscanf(request_line, "%15s %255s %15s", method, raw_url_full,
               http_version) != 3) {
        fprintf(stderr, "[ERROR] parse_request_url: Malformed request line\n");
        return NULL;
    }

    params->count = 0;

    char *working_raw = strdup(raw_url_full);
    if (!working_raw) {
        perror("Failed to allocate memory for URL copy");
        return NULL;
    }

    char *query_start = strchr(working_raw, '?');
    if (query_start) {
        *query_start = '\0'; 

    }

    char decoded_path[MAX_PATH_LEN];
    if (url_decode(decoded_path, working_raw, sizeof(decoded_path)) != 0) {
        fprintf(stderr, "[SECURITY] Invalid URL encoding in path\n");
        free(working_raw);
        return NULL;
    }

    char canonical_path[MAX_PATH_LEN];
    if (canonicalize_path(canonical_path, decoded_path, sizeof(canonical_path)) != 0) {
        fprintf(stderr, "[SECURITY] Path canonicalization failed\n");
        free(working_raw);
        return NULL;
    }

    char *path_check = strdup(canonical_path);
    if (path_check) {
        char *token = strtok(path_check, "/");
        while (token) {
            if (!is_safe_path_component(token)) {
                fprintf(stderr, "[SECURITY] Unsafe path component: %s\n", token);
                free(path_check);
                free(working_raw);
                return NULL;
            }
            token = strtok(NULL, "/");
        }
        free(path_check);
    }
    
    if (query_start) {
        char *query_string = query_start + 1; 

        char *pair;
        char *saveptr;

        pair = strtok_r(query_string, "&", &saveptr);
        while (pair && params->count < MAX_URL_PARAMS) {
            char *equals = strchr(pair, '=');
            if (equals) {
                *equals = '\0'; 

                char *raw_key = pair;
                char *raw_val = equals + 1;

                if (url_decode(params->params[params->count].key, raw_key, MAX_KEY_LEN) == 0 &&
                    url_decode(params->params[params->count].value, raw_val, MAX_VALUE_LEN) == 0) {
                    params->count++;
                }
            }
            pair = strtok_r(NULL, "&", &saveptr);
        }
    }

    char *final_path = strdup(canonical_path);
    free(working_raw);
    return final_path;
}

bool serve_static_file(const char *request_path_relative_to_static) {
  char full_static_path[MAX_PATH_LEN]; 

  if (strstr(request_path_relative_to_static, "..") != NULL) {
    fprintf(stderr, "[SECURITY] Attempted directory traversal: %s\n",
            request_path_relative_to_static);

    const char *forbidden_response =
        "HTTP/1.1 403 Forbidden\r\nContent-Length: 0\r\n\r\n";
    send(current_client_socket, forbidden_response, strlen(forbidden_response), 0);
    return true; 
  }

  snprintf(full_static_path, sizeof(full_static_path), "%s%s", STATIC_DIR,
           request_path_relative_to_static);

  FILE *fp = fopen(full_static_path, "rb");
  if (fp == NULL) {
    fprintf(stderr,
            "[ERROR] serve_static_file: File '%s' not found or could not be opened. %s\n",
            full_static_path, strerror(errno)); 
    return false; 
  }

  struct stat st; 

  if (fstat(fileno(fp), &st) < 0) {
    perror("fstat error");
    fprintf(stderr, "[ERROR] serve_static_file: fstat failed for '%s'.\n",
            full_static_path);
    fclose(fp); 

    const char *server_error_response =
        "HTTP/1.1 500 Internal Server Error\r\nContent-Length: 0\r\n\r\n";
    send(current_client_socket, server_error_response, strlen(server_error_response), 0);
    return true; 
  }

  long file_size = st.st_size; 
  const char *mime_type = get_mime_type(full_static_path); 

  char http_header[BUFFER_SIZE]; 

  snprintf(http_header, sizeof(http_header),
           "HTTP/1.1 200 OK\r\n"
           "Content-Type: %s\r\n"      
           "Content-Length: %ld\r\n"   
           "Connection: close\r\n"     
           "\r\n",                    
           mime_type, file_size);

  if (send(current_client_socket, http_header, strlen(http_header), 0) < 0) {
    perror("Error sending static file header");
    fprintf(stderr, "[ERROR] serve_static_file: Failed to send header for '%s'.\n", full_static_path);
    fclose(fp);
    return true; 
  }

  char file_buffer[BUFFER_SIZE]; 
  size_t bytes_read;             

  while ((bytes_read = fread(file_buffer, 1, sizeof(file_buffer), fp)) > 0) {
    if (send(current_client_socket, file_buffer, bytes_read, 0) < 0) {
      perror("Error sending static file content");
      fprintf(stderr, "[ERROR] serve_static_file: Failed to send content for '%s'.\n", full_static_path);
      break; 
    }
  }

  fclose(fp); 
  return true; 
}