/**
 * Tests for frontend/src/lib/export.ts
 *
 * Covers:
 *   - Unit tests for specific export format details
 *   - Property 7: Markdown export round-trip completeness
 *
 * **Validates: Requirements 11.1, 11.2, 11.3, 11.4**
 */

import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
import * as fc from "fast-check";
import {
  exportConversation,
  exportSingleResponse,
  exportAllSavedResponses,
} from "./export";
import type {
  Citation,
  Conversation,
  Message,
  QueryResult,
  SavedResponse,
} from "../types";

// ---------------------------------------------------------------------------
// DOM stubs — jsdom doesn't implement URL.createObjectURL or anchor.click
// ---------------------------------------------------------------------------

let downloadedContent: string | null = null;
let downloadedFilename: string | null = null;

beforeEach(() => {
  downloadedContent = null;
  downloadedFilename = null;

  // Stub URL.createObjectURL / revokeObjectURL
  vi.stubGlobal("URL", {
    createObjectURL: (_blob: Blob) => {
      // Capture blob content synchronously via FileReaderSync isn't available
      // in jsdom; instead we intercept via the Blob constructor mock below.
      return "blob:mock-url";
    },
    revokeObjectURL: vi.fn(),
  });

  // Intercept anchor click to capture filename and content
  const originalCreateElement = document.createElement.bind(document);
  vi.spyOn(document, "createElement").mockImplementation((tag: string) => {
    const el = originalCreateElement(tag);
    if (tag === "a") {
      Object.defineProperty(el, "click", {
        value: () => {
          downloadedFilename = (el as HTMLAnchorElement).download;
        },
        writable: true,
      });
    }
    return el;
  });

  // Intercept Blob to capture content
  vi.stubGlobal(
    "Blob",
    class MockBlob {
      content: string;
      type: string;
      constructor(parts: BlobPart[], options?: BlobPropertyBag) {
        this.content = parts.join("");
        this.type = options?.type ?? "";
        downloadedContent = this.content;
      }
    }
  );
});

afterEach(() => {
  vi.restoreAllMocks();
  vi.unstubAllGlobals();
});

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

function makeQueryResult(citations: Citation[]): QueryResult {
  return {
    citations,
    domains_searched: [],
    sections_retrieved: citations.length,
    timing: {},
    token_usage: { total_tokens: 0 },
  };
}

function makeCitation(
  index: number,
  title: string,
  domain: string,
  source_url?: string
): Citation {
  return { index, domain, title, source_url };
}

function makeConversation(
  messages: Message[],
  results: Record<string, QueryResult>
): Conversation {
  return {
    id: "conv-1",
    title: "Test conversation",
    created_at: "2024-01-15T00:00:00Z",
    last_active_at: "2024-01-15T00:00:00Z",
    messages,
    history: [],
    results,
  };
}

// ---------------------------------------------------------------------------
// Unit tests — exportSingleResponse
// ---------------------------------------------------------------------------

describe("exportSingleResponse", () => {
  it("includes YAML front-matter with date, model, and type fields", () => {
    const result = makeQueryResult([]);
    exportSingleResponse("What is the rule?", "The rule is X.", result);

    expect(downloadedContent).toContain("---");
    expect(downloadedContent).toMatch(/date: \d{4}-\d{2}-\d{2}/);
    expect(downloadedContent).toContain("model: claude-3-5-sonnet");
    expect(downloadedContent).toContain("type: response");
  });

  it("includes the question as an H1 heading", () => {
    const result = makeQueryResult([]);
    exportSingleResponse("What is the rule?", "The rule is X.", result);

    expect(downloadedContent).toContain("# What is the rule?");
  });

  it("includes the answer body", () => {
    const result = makeQueryResult([]);
    exportSingleResponse("What is the rule?", "The rule is X.", result);

    expect(downloadedContent).toContain("The rule is X.");
  });

  it("includes a Sources section with citations when present", () => {
    const result = makeQueryResult([
      makeCitation(1, "Section A", "example.com", "https://example.com/a"),
      makeCitation(2, "Section B", "other.com"),
    ]);
    exportSingleResponse("What is the rule?", "The rule is X.", result);

    expect(downloadedContent).toContain("## Sources");
    expect(downloadedContent).toContain(
      "[Section A](https://example.com/a) — example.com"
    );
    expect(downloadedContent).toContain("Section B — other.com");
  });

  it("omits the Sources section when there are no citations", () => {
    const result = makeQueryResult([]);
    exportSingleResponse("What is the rule?", "The rule is X.", result);

    expect(downloadedContent).not.toContain("## Sources");
  });

  it("renders citations with source_url as hyperlinks", () => {
    const result = makeQueryResult([
      makeCitation(1, "My Section", "example.com", "https://example.com"),
    ]);
    exportSingleResponse("Q?", "A.", result);

    expect(downloadedContent).toContain("[My Section](https://example.com)");
  });

  it("renders citations without source_url as plain text", () => {
    const result = makeQueryResult([
      makeCitation(1, "My Section", "example.com"),
    ]);
    exportSingleResponse("Q?", "A.", result);

    expect(downloadedContent).toContain("1. My Section — example.com");
    expect(downloadedContent).not.toContain("[My Section]");
  });

  it("generates a filename with the correct pattern", () => {
    const result = makeQueryResult([]);
    exportSingleResponse("What are the rules?", "Answer.", result);

    // Filename: health-marketing-{YYYYMMDD}-{slug}.md
    expect(downloadedFilename).toMatch(
      /^health-marketing-\d{8}-what-are-the-rules\.md$/
    );
  });

  it("slugifies the question: lowercase, hyphens, max 40 chars", () => {
    const result = makeQueryResult([]);
    exportSingleResponse(
      "What Are The ADVERTISING Rules For Chiropractors In New Zealand?",
      "Answer.",
      result
    );

    // slug should be lowercase, hyphens, truncated to 40 chars
    expect(downloadedFilename).toMatch(/^health-marketing-\d{8}-[a-z0-9-]+\.md$/);
    const slug = downloadedFilename!.replace(/^health-marketing-\d{8}-/, "").replace(/\.md$/, "");
    expect(slug.length).toBeLessThanOrEqual(40);
  });
});

// ---------------------------------------------------------------------------
// Unit tests — exportConversation
// ---------------------------------------------------------------------------

describe("exportConversation", () => {
  it("includes type: conversation in front-matter", () => {
    const messages: Message[] = [
      { role: "user", content: "Question 1?" },
      { role: "assistant", content: "Answer 1." },
    ];
    const results = { "1": makeQueryResult([]) };
    const conv = makeConversation(messages, results);

    exportConversation(conv);

    expect(downloadedContent).toContain("type: conversation");
  });

  it("generates one H1 section per Q&A pair", () => {
    const messages: Message[] = [
      { role: "user", content: "Question 1?" },
      { role: "assistant", content: "Answer 1." },
      { role: "user", content: "Question 2?" },
      { role: "assistant", content: "Answer 2." },
    ];
    const results = {
      "1": makeQueryResult([]),
      "3": makeQueryResult([]),
    };
    const conv = makeConversation(messages, results);

    exportConversation(conv);

    expect(downloadedContent).toContain("# Question 1?");
    expect(downloadedContent).toContain("# Question 2?");
    expect(downloadedContent).toContain("Answer 1.");
    expect(downloadedContent).toContain("Answer 2.");
  });

  it("uses the first user question for the filename slug", () => {
    const messages: Message[] = [
      { role: "user", content: "First question here?" },
      { role: "assistant", content: "Answer." },
    ];
    const conv = makeConversation(messages, { "1": makeQueryResult([]) });

    exportConversation(conv);

    expect(downloadedFilename).toMatch(/first-question-here/);
  });
});

// ---------------------------------------------------------------------------
// Unit tests — exportAllSavedResponses
// ---------------------------------------------------------------------------

describe("exportAllSavedResponses", () => {
  it("includes type: saved-responses in front-matter", () => {
    exportAllSavedResponses([]);

    expect(downloadedContent).toContain("type: saved-responses");
  });

  it("concatenates multiple saved responses with --- separators", () => {
    const saved: SavedResponse[] = [
      {
        id: "conv-1:1",
        question: "Q1?",
        answer: "A1.",
        saved_at: "2024-01-15T00:00:00Z",
        source_conversation_id: "conv-1",
        source_conversation_title: "Conv 1",
        msg_index: 1,
        messages_pair: [],
        history_pair: [],
        result: makeQueryResult([makeCitation(1, "Sec A", "a.com")]),
      },
      {
        id: "conv-2:1",
        question: "Q2?",
        answer: "A2.",
        saved_at: "2024-01-16T00:00:00Z",
        source_conversation_id: "conv-2",
        source_conversation_title: "Conv 2",
        msg_index: 1,
        messages_pair: [],
        history_pair: [],
        result: makeQueryResult([makeCitation(1, "Sec B", "b.com")]),
      },
    ];

    exportAllSavedResponses(saved);

    expect(downloadedContent).toContain("# Q1?");
    expect(downloadedContent).toContain("# Q2?");
    expect(downloadedContent).toContain("---");
  });

  it("uses saved-responses in the filename", () => {
    exportAllSavedResponses([]);

    expect(downloadedFilename).toMatch(/saved-responses\.md$/);
  });
});

// ---------------------------------------------------------------------------
// Property 7: Markdown export round-trip completeness
//
// For any completed assistant message with citations, the Markdown export
// generated by the browser SHALL contain the question text, the answer body,
// and a Sources section listing every citation title that was present in the
// QueryResult.
//
// **Validates: Requirements 11.3**
// ---------------------------------------------------------------------------

describe("Property 7: Markdown export round-trip completeness", () => {
  // Arbitraries
  const nonEmptyString = fc.string({ minLength: 1, maxLength: 200 });

  const citationArb = fc
    .record({
      index: fc.integer({ min: 1, max: 20 }),
      domain: fc.stringMatching(/^[a-z]{3,10}\.[a-z]{2,4}$/),
      title: nonEmptyString,
      source_url: fc.option(
        fc.webUrl({ validSchemes: ["https"] }),
        { nil: undefined }
      ),
    })
    .map(
      (c): Citation => ({
        index: c.index,
        domain: c.domain,
        title: c.title,
        source_url: c.source_url ?? undefined,
      })
    );

  const queryResultArb = fc
    .array(citationArb, { minLength: 0, maxLength: 10 })
    .map(
      (citations): QueryResult => ({
        citations,
        domains_searched: [],
        sections_retrieved: citations.length,
        timing: {},
        token_usage: { total_tokens: 0 },
      })
    );

  it("export contains question, answer, and all citation titles", () => {
    fc.assert(
      fc.property(nonEmptyString, nonEmptyString, queryResultArb, (question, answer, result) => {
        exportSingleResponse(question, answer, result);

        const content = downloadedContent ?? "";

        // Must contain the question as H1
        expect(content).toContain(`# ${question}`);

        // Must contain the answer body
        expect(content).toContain(answer);

        // Must contain every citation title
        for (const citation of result.citations) {
          expect(content).toContain(citation.title);
        }

        // If there are citations, must have a Sources section
        if (result.citations.length > 0) {
          expect(content).toContain("## Sources");
        }
      }),
      { numRuns: 100 }
    );
  });

  it("export contains all citation titles for a full conversation", () => {
    const messagesPairArb = fc
      .tuple(nonEmptyString, nonEmptyString)
      .map(([q, a]): Message[] => [
        { role: "user", content: q },
        { role: "assistant", content: a },
      ]);

    fc.assert(
      fc.property(
        fc.array(fc.tuple(messagesPairArb, queryResultArb), {
          minLength: 1,
          maxLength: 5,
        }),
        (pairs) => {
          const messages: Message[] = pairs.flatMap(([msgs]) => msgs);
          const results: Record<string, QueryResult> = {};
          pairs.forEach(([_msgs, result], i) => {
            // assistant message index = i*2 + 1
            results[String(i * 2 + 1)] = result;
          });

          const conv = makeConversation(messages, results);
          exportConversation(conv);

          const content = downloadedContent ?? "";

          // Every question and answer must appear
          pairs.forEach(([msgs, result]) => {
            const question = msgs[0].content;
            const answer = msgs[1].content;
            expect(content).toContain(`# ${question}`);
            expect(content).toContain(answer);

            // Every citation title must appear
            for (const citation of result.citations) {
              expect(content).toContain(citation.title);
            }
          });
        }
      ),
      { numRuns: 50 }
    );
  });
});