/**
 * imagesToScratchpadPaths unit tests: input conversion when the session model does not support
 * images -- data URL images are written to the session scratchpad and their paths appended to the
 * user text; http(s) URLs are referenced as-is; image messages are removed from the input;
 * image-free input is returned unchanged; images that fail to parse are replaced with an explanatory line.
 *
 * Plus appendAttachmentLines, the placement rule both attachment-line producers share (the
 * images above and the server's `[attached file: …]` uploads).
 */
import { afterEach, beforeEach, describe, expect, it } from "vitest";
import { mkdtemp, readFile, readdir, rm } from "node:fs/promises";
import { tmpdir } from "node:os";
import path from "node:path";
import { appendAttachmentLines, imagesToScratchpadPaths } from "../src/internal/session-support.js";
import {
  buildHandoffMessage,
  buildModelSwitchMessage,
  buildScheduledMessage,
  buildSkillsMessage,
  imageUrlMessage,
  parseHandoffMessage,
  parseModelSwitchMessage,
  userText,
} from "../src/omnimessage/index.js";
import type { TextPayload } from "../src/omnimessage/index.js";

const PNG_1X1 = Buffer.from(
  "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8z8BQDwAEhQGAhKmMIQAAAABJRU5ErkJggg==",
  "base64",
);
const DATA_URL = `data:image/png;base64,${PNG_1X1.toString("base64")}`;

let tmp: string;

beforeEach(async () => {
  tmp = await mkdtemp(path.join(tmpdir(), "penguin-inputimg-"));
});

afterEach(async () => {
  await rm(tmp, { recursive: true, force: true });
});

describe("imagesToScratchpadPaths", () => {
  it("data URL images are saved to disk, paths appended to the user text, image messages removed", async () => {
    const dir = path.join(tmp, "scratch", "session-1"); // auto-created if the directory doesn't exist
    const out = await imagesToScratchpadPaths(
      [userText("Look at these two images"), imageUrlMessage(DATA_URL), imageUrlMessage(DATA_URL)],
      dir,
    );

    expect(out).toHaveLength(1);
    const p = out[0]!.payload as TextPayload;
    expect(p.type).toBe("text");
    expect(p.role).toBe("user");
    expect(p.text.startsWith("Look at these two images\n\n")).toBe(true);
    const paths = [...p.text.matchAll(/\[attached image: ([^\]]+)\]/g)].map((m) => m[1]!);
    expect(paths).toHaveLength(2);

    // The saved content matches the original image; filename = upload-<8-char random hex>.<extension by mime type>.
    const files = await readdir(dir);
    expect(files).toHaveLength(2);
    for (const f of paths) {
      expect(path.dirname(f)).toBe(dir);
      expect(path.basename(f)).toMatch(/^upload-[0-9a-f]{8}\.png$/);
      expect(await readFile(f)).toEqual(PNG_1X1);
    }
    // The two images' random names differ from each other.
    expect(new Set(paths).size).toBe(2);
  });

  it("http(s) URLs are not saved but referenced as-is; image-only input gets a paths-only text message", async () => {
    const out = await imagesToScratchpadPaths([imageUrlMessage("https://example.com/a.png")], tmp);
    expect(out).toHaveLength(1);
    const p = out[0]!.payload as TextPayload;
    expect(p.type).toBe("text");
    expect(p.text).toBe("[attached image: https://example.com/a.png]");
    expect(await readdir(tmp)).toHaveLength(0);
  });

  it("input without images is returned as-is (never touches the filesystem)", async () => {
    const input = [userText("plain text")];
    const out = await imagesToScratchpadPaths(input, path.join(tmp, "untouched"));
    expect(out).toBe(input);
  });

  it("an unparsable image is replaced with an explanatory line, never silently dropped", async () => {
    const out = await imagesToScratchpadPaths(
      [userText("hi"), imageUrlMessage("data:text/plain,oops")],
      tmp,
    );
    const p = out[0]!.payload as TextPayload;
    expect(p.text).toContain("could not be saved");
  });
});

/** Text of the message at `index` of an appendAttachmentLines result. */
const textAt = (out: ReturnType<typeof appendAttachmentLines>, index: number): string =>
  (out[index]!.payload as TextPayload).text;

describe("appendAttachmentLines placement", () => {
  const LINE = "[attached file: /d/scratchpad/s1/report.pdf]";

  it("appends to the last user text message", () => {
    const out = appendAttachmentLines([userText("first"), userText("second")], [LINE]);
    expect(out).toHaveLength(2);
    expect(textAt(out, 0)).toBe("first");
    expect(textAt(out, 1)).toBe(`second\n\n${LINE}`);
  });

  it("no user text at all: the lines become a message of their own", () => {
    const out = appendAttachmentLines([], [LINE]);
    expect(out).toHaveLength(1);
    expect(textAt(out, 0)).toBe(LINE);
  });

  it("a whole-message origin block is left alone; the lines get their own message", () => {
    // The composer's files-only-plus-staged-handoff shape: the only text message is the origin
    // block, and both of these parsers require the block to be the WHOLE message — appending to
    // it would render the raw marker in a user bubble instead of a one-line banner.
    for (const block of [
      buildHandoffMessage({ agentId: "alpha", agentName: "Alpha", sessionId: "s0" }),
      buildModelSwitchMessage({ sessionId: "s0", prevModelId: "m0" }),
    ]) {
      const out = appendAttachmentLines([userText(block)], [LINE]);
      expect(out).toHaveLength(2);
      expect(textAt(out, 0)).toBe(block);
      expect(textAt(out, 1)).toBe(LINE);
    }
    // …and the blocks still parse afterwards, which is the property that actually matters.
    const handoff = appendAttachmentLines(
      [userText(buildHandoffMessage({ agentId: "alpha", sessionId: "s0" }))],
      [LINE],
    );
    expect(parseHandoffMessage(textAt(handoff, 0))?.agentId).toBe("alpha");
    const switched = appendAttachmentLines(
      [userText(buildModelSwitchMessage({ sessionId: "s0" }))],
      [LINE],
    );
    expect(parseModelSwitchMessage(textAt(switched, 0))?.sessionId).toBe("s0");
  });

  it("prefix blocks still take the lines after their body ([use_skills] / [scheduled_task])", () => {
    // The other direction: these two are parsed at index 0 and keep the body that follows, so a
    // trailing line is an ordinary footnote to the message and must NOT start a new one.
    for (const message of [
      buildSkillsMessage(["web-design"], "fix the layout"),
      buildScheduledMessage("nightly", "2026-07-29T02:00:00Z", "run the report"),
    ]) {
      const out = appendAttachmentLines([userText(message)], [LINE]);
      expect(out).toHaveLength(1);
      expect(textAt(out, 0)).toBe(`${message}\n\n${LINE}`);
    }
  });

  it("an earlier ordinary message wins over a trailing origin block", () => {
    const block = buildHandoffMessage({ agentId: "alpha" });
    const out = appendAttachmentLines([userText("hello"), userText(block)], [LINE]);
    expect(out).toHaveLength(2);
    expect(textAt(out, 0)).toBe(`hello\n\n${LINE}`);
    expect(textAt(out, 1)).toBe(block);
  });
});