/**
 * Ghost Content API Client
 * Read-only API for published content using native fetch
 */

import type { IBrowseOptions, IReadOptions, IGhostAPIResponse, IGhostErrorResponse } from './ghost.types.js';

export interface IGhostContentAPIOptions {
  url: string;
  key: string;
  version?: string;
  ghostPath?: string;
}

export class GhostContentAPI {
  private url: string;
  private key: string;
  private version: string;
  private ghostPath: string;

  constructor(options: IGhostContentAPIOptions) {
    this.url = options.url.replace(/\/$/, ''); // Remove trailing slash
    this.key = options.key;
    this.version = options.version || 'v3';
    this.ghostPath = options.ghostPath || 'ghost';

    if (!this.url) {
      throw new Error('GhostContentAPI: url is required');
    }
    if (!this.key) {
      throw new Error('GhostContentAPI: key is required');
    }
  }

  /**
   * Build the API prefix based on version
   */
  private getAPIPrefix(): string {
    // v5+ doesn't need version prefix
    if (this.version === 'v5' || this.version === 'v6' || this.version.match(/^v[5-9]\.\d+/)) {
      return `/content/`;
    }
    // v2-v4 and canary need version prefix
    return `/${this.version}/content/`;
  }

  /**
   * Build full API URL
   */
  private buildUrl(resource: string, identifier?: string, params?: Record<string, any>): string {
    const apiPrefix = this.getAPIPrefix();
    let endpoint = `${this.url}/${this.ghostPath}/api${apiPrefix}${resource}/`;

    if (identifier) {
      endpoint += `${identifier}/`;
    }

    // Add key to params
    const queryParams = {
      key: this.key,
      ...params
    };

    // Build query string
    const queryString = Object.keys(queryParams)
      .filter(key => queryParams[key] !== undefined && queryParams[key] !== null)
      .map(key => {
        const value = Array.isArray(queryParams[key])
          ? queryParams[key].join(',')
          : queryParams[key];
        return `${key}=${encodeURIComponent(value)}`;
      })
      .join('&');

    return queryString ? `${endpoint}?${queryString}` : endpoint;
  }

  /**
   * Make API request
   */
  private async makeRequest<T>(
    resource: string,
    identifier?: string,
    params?: Record<string, any>
  ): Promise<T | T[]> {
    const url = this.buildUrl(resource, identifier, params);

    try {
      const response = await fetch(url, {
        method: 'GET',
        headers: {
          'Accept': 'application/json',
          'Accept-Version': this.version.match(/^\d+\.\d+$/) ? `v${this.version}` : this.version,
          'User-Agent': 'GhostContentAPI/2.0'
        }
      });

      if (!response.ok) {
        const errorData: IGhostErrorResponse = await response.json().catch(() => ({
          errors: [{ type: 'UnknownError', message: response.statusText }]
        }));

        const error = errorData.errors?.[0];
        const err = new Error(error?.message || response.statusText);
        Object.assign(err, {
          name: error?.type || 'GhostContentAPIError',
          statusCode: response.status,
          ...error
        });
        throw err;
      }

      const data: IGhostAPIResponse<T> = await response.json();

      // Extract the resource data
      const resourceData = data[resource];
      if (!resourceData) {
        throw new Error(`Response missing ${resource} property`);
      }

      // If it's an array and has meta, attach meta to the array
      if (Array.isArray(resourceData) && data.meta) {
        return Object.assign(resourceData, { meta: data.meta });
      }

      // If it's an array with single item and no meta, return the item
      if (Array.isArray(resourceData) && resourceData.length === 1 && !data.meta) {
        return resourceData[0];
      }

      return resourceData as T | T[];
    } catch (error) {
      throw error;
    }
  }

  /**
   * Create resource API methods
   */
  public posts = {
    browse: (options?: IBrowseOptions) => this.makeRequest('posts', undefined, options),
    read: (options: IReadOptions) => {
      if (options.slug) {
        return this.makeRequest('posts', `slug/${options.slug}`, options);
      }
      if (options.id) {
        return this.makeRequest('posts', options.id, options);
      }
      throw new Error('Must provide id or slug');
    }
  };

  public pages = {
    browse: (options?: IBrowseOptions) => this.makeRequest('pages', undefined, options),
    read: (options: IReadOptions) => {
      if (options.slug) {
        return this.makeRequest('pages', `slug/${options.slug}`, options);
      }
      if (options.id) {
        return this.makeRequest('pages', options.id, options);
      }
      throw new Error('Must provide id or slug');
    }
  };

  public tags = {
    browse: (options?: IBrowseOptions) => this.makeRequest('tags', undefined, options),
    read: (options: IReadOptions) => {
      if (options.slug) {
        return this.makeRequest('tags', `slug/${options.slug}`, options);
      }
      if (options.id) {
        return this.makeRequest('tags', options.id, options);
      }
      throw new Error('Must provide id or slug');
    }
  };

  public authors = {
    browse: (options?: IBrowseOptions) => this.makeRequest('authors', undefined, options),
    read: (options: IReadOptions) => {
      if (options.slug) {
        return this.makeRequest('authors', `slug/${options.slug}`, options);
      }
      if (options.id) {
        return this.makeRequest('authors', options.id, options);
      }
      throw new Error('Must provide id or slug');
    }
  };
}