import { describe, expect, test } from "bun:test"
import { toMessagePreview } from "./message-preview"

describe("toMessagePreview", () => {
  test("leaves plain prose alone but for its whitespace", () => {
    expect(toMessagePreview("  make the sidebar labels shorter  "))
      .toBe("make the sidebar labels shorter")
  })

  test("flattens the lines a clamp would otherwise spend", () => {
    // Two clamped lines used to buy two bullets and nothing that said what the
    // message was about.
    expect(toMessagePreview("Fix these:\n\n- the router\n- the store\n- the tests"))
      .toBe("Fix these: the router the store the tests")
  })

  test("unwraps emphasis, strikethrough and inline code", () => {
    expect(toMessagePreview("**Done** — the ~~old~~ `parseTranscript` path is gone"))
      .toBe("Done — the old parseTranscript path is gone")
    expect(toMessagePreview("*maybe* _really_ ***very*** sure")).toBe("maybe really very sure")
  })

  test("leaves double underscores alone, dunders and bold alike", () => {
    // `__init__` and `__bold__` are the same string; no rule tells them apart.
    // Showing the underscores is a blemish, turning `__init__` into `init`
    // changes what the message says — so doubles are left as written.
    expect(toMessagePreview("call __init__ first")).toBe("call __init__ first")
    expect(toMessagePreview("this is __bold__")).toBe("this is __bold__")
  })

  test("keeps a link's words and drops its href", () => {
    expect(toMessagePreview("see [the docs](https://example.com/a_b) first"))
      .toBe("see the docs first")
    expect(toMessagePreview("![a diagram](x.png) explains it")).toBe("a diagram explains it")
    expect(toMessagePreview("see [the docs][docs]")).toBe("see the docs")
    expect(toMessagePreview("at <https://example.com/x>")).toBe("at https://example.com/x")
  })

  test("drops headings, quotes, rules and task boxes but keeps their text", () => {
    expect(toMessagePreview("## Plan\n\n> quoting you\n\n---\n\n- [x] shipped"))
      .toBe("Plan quoting you shipped")
  })

  test("keeps the code inside a fence and drops the fence", () => {
    // A message that is mostly code would otherwise preview as empty.
    expect(toMessagePreview("Try:\n```ts\nconst x = 1\n```"))
      .toBe("Try: const x = 1")
  })

  test("does not eat underscores inside identifiers", () => {
    // The rule that would do real damage: these are names, not emphasis, and
    // CommonMark agrees — intraword underscores don't emphasise.
    expect(toMessagePreview("rename retry_count_ms today")).toBe("rename retry_count_ms today")
    expect(toMessagePreview("set last_turn_ended_at")).toBe("set last_turn_ended_at")
  })

  test("does not eat a lone asterisk or a bare underscore", () => {
    expect(toMessagePreview("2 * 3 and a _ on its own")).toBe("2 * 3 and a _ on its own")
    expect(toMessagePreview("glob for *.ts files")).toBe("glob for *.ts files")
  })

  test("leaves tags alone — an agent that wrote one meant it", () => {
    expect(toMessagePreview("wrap it in <system-reminder> please"))
      .toBe("wrap it in <system-reminder> please")
  })

  test("survives text that is nothing but markup", () => {
    expect(toMessagePreview("---")).toBe("")
    expect(toMessagePreview("```\n```")).toBe("")
    expect(toMessagePreview("")).toBe("")
  })
})