import type {
  StartInspectionResponse,
  InspectionResult,
  IssueListResponse,
  IssueFilters,
  PaginatedResponse,
  HistoryParams,
  TrendResponse,
} from "@/types/inspection";
import type {
  StartSiteInspectionResponse,
  SiteInspectionResult,
  InspectPageResponse,
} from "@/types/site-inspection";

const API_BASE_URL =
  process.env.NEXT_PUBLIC_API_URL ?? "";

/** API 에러 클래스 */
export class ApiError extends Error {
  status: number;
  detail: string;

  constructor(status: number, detail: string) {
    super(detail);
    this.name = "ApiError";
    this.status = status;
    this.detail = detail;
  }
}

/** API 클라이언트 */
class ApiClient {
  private baseUrl: string;

  constructor(baseUrl: string) {
    this.baseUrl = baseUrl;
  }

  private async request<T>(path: string, options?: RequestInit): Promise<T> {
    const response = await fetch(`${this.baseUrl}${path}`, {
      headers: { "Content-Type": "application/json" },
      ...options,
    });

    if (!response.ok) {
      let detail = "요청 처리 중 오류가 발생했습니다";
      try {
        const error = await response.json();
        detail = error.detail || detail;
      } catch {
        // JSON 파싱 실패 시 기본 메시지 사용
      }
      throw new ApiError(response.status, detail);
    }

    return response.json();
  }

  /** 검사 시작 */
  async startInspection(url: string): Promise<StartInspectionResponse> {
    return this.request("/api/inspections", {
      method: "POST",
      body: JSON.stringify({ url }),
    });
  }

  /** 검사 결과 조회 */
  async getInspection(id: string): Promise<InspectionResult> {
    return this.request(`/api/inspections/${id}`);
  }

  /** 이슈 목록 조회 */
  async getIssues(
    id: string,
    filters?: IssueFilters
  ): Promise<IssueListResponse> {
    const params = new URLSearchParams();
    if (filters?.category && filters.category !== "all") {
      params.set("category", filters.category);
    }
    if (filters?.severity && filters.severity !== "all") {
      params.set("severity", filters.severity);
    }
    const qs = params.toString();
    return this.request(`/api/inspections/${id}/issues${qs ? `?${qs}` : ""}`);
  }

  /** 이력 목록 조회 (페이지네이션) */
  async getInspections(params: HistoryParams): Promise<PaginatedResponse> {
    const qs = new URLSearchParams();
    qs.set("page", String(params.page || 1));
    qs.set("limit", String(params.limit || 20));
    if (params.url) qs.set("url", params.url);
    if (params.sort) qs.set("sort", params.sort);
    return this.request(`/api/inspections?${qs}`);
  }

  /** 트렌드 데이터 조회 */
  async getTrend(url: string, limit = 10): Promise<TrendResponse> {
    const qs = new URLSearchParams({ url, limit: String(limit) });
    return this.request(`/api/inspections/trend?${qs}`);
  }

  /** PDF 다운로드 */
  async downloadPdf(id: string): Promise<void> {
    const response = await fetch(
      `${this.baseUrl}/api/inspections/${id}/report/pdf`
    );
    if (!response.ok) {
      throw new ApiError(response.status, "PDF 다운로드에 실패했습니다");
    }
    const blob = await response.blob();
    const url = URL.createObjectURL(blob);
    const a = document.createElement("a");
    a.href = url;
    a.download =
      response.headers.get("content-disposition")?.split("filename=")[1] ||
      `web-inspector-report.pdf`;
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
    URL.revokeObjectURL(url);
  }

  /** JSON 다운로드 */
  async downloadJson(id: string): Promise<void> {
    const response = await fetch(
      `${this.baseUrl}/api/inspections/${id}/report/json`
    );
    if (!response.ok) {
      throw new ApiError(response.status, "JSON 다운로드에 실패했습니다");
    }
    const blob = await response.blob();
    const url = URL.createObjectURL(blob);
    const a = document.createElement("a");
    a.href = url;
    a.download =
      response.headers.get("content-disposition")?.split("filename=")[1] ||
      `web-inspector-report.json`;
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
    URL.revokeObjectURL(url);
  }

  /** SSE 스트림 URL 반환 */
  getStreamUrl(inspectionId: string): string {
    return `${this.baseUrl}/api/inspections/${inspectionId}/stream`;
  }

  // ─────────────────────────────────────────────────────
  // 사이트 전체 검사 API
  // ─────────────────────────────────────────────────────

  /** 사이트 전체 검사 시작 */
  async startSiteInspection(
    url: string,
    maxPages?: number,
    maxDepth?: number,
    concurrency?: number
  ): Promise<StartSiteInspectionResponse> {
    return this.request("/api/site-inspections", {
      method: "POST",
      body: JSON.stringify({
        url,
        max_pages: maxPages,
        max_depth: maxDepth,
        concurrency: concurrency,
      }),
    });
  }

  /** 사이트 검사 결과 조회 */
  async getSiteInspection(id: string): Promise<SiteInspectionResult> {
    return this.request(`/api/site-inspections/${id}`);
  }

  /** 특정 페이지 수동 검사 */
  async inspectPage(
    siteInspectionId: string,
    pageUrl: string
  ): Promise<InspectPageResponse> {
    return this.request(
      `/api/site-inspections/${siteInspectionId}/inspect-page`,
      {
        method: "POST",
        body: JSON.stringify({ url: pageUrl }),
      }
    );
  }

  /** 사이트 검사 SSE 스트림 URL 반환 */
  getSiteStreamUrl(siteInspectionId: string): string {
    return `${this.baseUrl}/api/site-inspections/${siteInspectionId}/stream`;
  }
}

export const api = new ApiClient(API_BASE_URL);