/**
 * test/http/approval-preview.test.ts (W1) — deriveApprovalPreview unit tests.
 *
 * Pure, never-throws derivation of a bounded, sanitized command/diff preview
 * from an untrusted hook tool_input. Node env (no DOM).
 */

import { describe, it, expect } from 'vitest'
import {
  deriveApprovalPreview,
  PREVIEW_MAX_LINES,
  PREVIEW_MAX_BYTES,
} from '../../src/http/approval-preview.js'
import type { ApprovalPreview, DiffFile } from '../../src/types.js'

/** Narrow a preview to its 'diff' variant (throws in-test if wrong shape). */
function asDiff(p: ApprovalPreview | null): DiffFile {
  expect(p).not.toBeNull()
  expect(p!.kind).toBe('diff')
  return (p as { kind: 'diff'; file: DiffFile }).file
}

describe('deriveApprovalPreview — Bash → command', () => {
  it('extracts the command string', () => {
    const p = deriveApprovalPreview('Bash', { command: 'ls -la', description: 'x' })
    expect(p).toEqual({ kind: 'command', text: 'ls -la' })
  })

  it('preserves newlines in a multi-line command', () => {
    const p = deriveApprovalPreview('Bash', { command: 'a\nb' })
    expect(p).toMatchObject({ kind: 'command' })
    expect((p as { text: string }).text).toContain('\n')
    expect((p as { text: string }).text).toBe('a\nb')
  })

  it('strips ANSI/control injection (ESC, BEL) from the command', () => {
    const p = deriveApprovalPreview('Bash', { command: '\x1b[31mrm\x1b[0m\x07' })
    const text = (p as { text: string }).text
    expect(text).not.toContain('\x1b')
    expect(text).not.toContain('\x07')
    expect(text).toBe('[31mrm[0m') // control bytes gone, printable payload remains
  })

  it('returns null when command is missing / not a string', () => {
    expect(deriveApprovalPreview('Bash', { description: 'x' })).toBeNull()
    expect(deriveApprovalPreview('Bash', { command: 42 })).toBeNull()
  })
})

describe('deriveApprovalPreview — Edit → diff', () => {
  it('builds one hunk with removed + added lines and correct counts', () => {
    const file = asDiff(
      deriveApprovalPreview('Edit', {
        file_path: '/p/f.ts',
        old_string: 'a\nb',
        new_string: 'c',
      }),
    )
    expect(file.newPath).toBe('/p/f.ts')
    expect(file.removed).toBe(2)
    expect(file.added).toBe(1)
    expect(file.hunks).toHaveLength(1)
    const kinds = file.hunks[0]!.lines.map((l) => `${l.kind}:${l.text}`)
    expect(kinds).toEqual(['removed:a', 'removed:b', 'added:c'])
  })

  it('sanitizes the file path (strips control chars)', () => {
    const file = asDiff(
      deriveApprovalPreview('Edit', {
        file_path: '/p/\x1b[2Jevil.ts',
        old_string: 'x',
        new_string: 'y',
      }),
    )
    expect(file.newPath).not.toContain('\x1b')
    expect(file.newPath).toBe('/p/[2Jevil.ts')
  })

  it('returns null for an Edit missing old_string', () => {
    expect(deriveApprovalPreview('Edit', { file_path: '/p/f', new_string: 'c' })).toBeNull()
  })
})

describe('deriveApprovalPreview — Write → all-added diff', () => {
  it('emits an all-added hunk with removed===0', () => {
    const file = asDiff(deriveApprovalPreview('Write', { file_path: '/p/f', content: 'x\ny' }))
    expect(file.removed).toBe(0)
    expect(file.added).toBe(2)
    expect(file.status).toBe('added')
    expect(file.hunks[0]!.lines.map((l) => l.kind)).toEqual(['added', 'added'])
  })

  it('returns null when content is not a string', () => {
    expect(deriveApprovalPreview('Write', { file_path: '/p/f' })).toBeNull()
  })
})

describe('deriveApprovalPreview — MultiEdit → one hunk per edit', () => {
  it('produces a hunk for each edit', () => {
    const file = asDiff(
      deriveApprovalPreview('MultiEdit', {
        file_path: '/p/f',
        edits: [
          { old_string: 'a', new_string: 'b' },
          { old_string: 'c', new_string: 'd' },
        ],
      }),
    )
    expect(file.hunks).toHaveLength(2)
    expect(file.removed).toBe(2)
    expect(file.added).toBe(2)
  })

  it('drops malformed edit entries; null when all are invalid', () => {
    expect(
      deriveApprovalPreview('MultiEdit', { file_path: '/p/f', edits: [{ old_string: 'a' }] }),
    ).toBeNull()
    const file = asDiff(
      deriveApprovalPreview('MultiEdit', {
        file_path: '/p/f',
        edits: [{ old_string: 'a' }, { old_string: 'x', new_string: 'y' }],
      }),
    )
    expect(file.hunks).toHaveLength(1)
  })

  it('returns null when edits is not an array', () => {
    expect(deriveApprovalPreview('MultiEdit', { file_path: '/p/f', edits: 'nope' })).toBeNull()
  })
})

describe('deriveApprovalPreview — NotebookEdit', () => {
  it('previews new_source as an all-added diff', () => {
    const file = asDiff(
      deriveApprovalPreview('NotebookEdit', { notebook_path: '/n.ipynb', new_source: 'print(1)' }),
    )
    expect(file.newPath).toBe('/n.ipynb')
    expect(file.added).toBe(1)
    expect(file.removed).toBe(0)
  })
})

describe('deriveApprovalPreview — truncation (DoS containment)', () => {
  it('caps line count and flags truncated for a huge command', () => {
    const command = Array.from({ length: PREVIEW_MAX_LINES + 20 }, (_, i) => `line${i}`).join('\n')
    const p = deriveApprovalPreview('Bash', { command })
    expect(p).toMatchObject({ kind: 'command', truncated: true })
    const text = (p as { text: string }).text
    expect(text.split('\n').length).toBeLessThanOrEqual(PREVIEW_MAX_LINES)
  })

  it('caps total bytes for a huge single-line blob', () => {
    const command = 'x'.repeat(PREVIEW_MAX_BYTES * 4)
    const p = deriveApprovalPreview('Bash', { command })
    expect(p).toMatchObject({ truncated: true })
    const text = (p as { text: string }).text
    expect(Buffer.byteLength(text, 'utf8')).toBeLessThanOrEqual(PREVIEW_MAX_BYTES)
  })

  it('caps a giant Write and keeps the serialized diff within the byte cap', () => {
    const content = Array.from({ length: 500 }, (_, i) => `row-${i}-`.repeat(50)).join('\n')
    const p = deriveApprovalPreview('Write', { file_path: '/p/f', content })
    expect(p).toMatchObject({ kind: 'diff', truncated: true })
    const file = asDiff(p)
    const emitted = file.hunks.flatMap((h) => h.lines)
    expect(emitted.length).toBeLessThanOrEqual(PREVIEW_MAX_LINES)
    const bytes = emitted.reduce((n, l) => n + Buffer.byteLength(l.text, 'utf8'), 0)
    expect(bytes).toBeLessThanOrEqual(PREVIEW_MAX_BYTES)
  })
})

describe('deriveApprovalPreview — unknown tools & malformed input (never throws)', () => {
  it('returns null for a non-previewable tool', () => {
    expect(deriveApprovalPreview('WebFetch', { url: 'http://x' })).toBeNull()
    expect(deriveApprovalPreview('ExitPlanMode', {})).toBeNull()
  })

  it('returns null for undefined tool name', () => {
    expect(deriveApprovalPreview(undefined, { command: 'ls' })).toBeNull()
  })

  it('returns null (never throws) for null / array / number / string tool_input', () => {
    expect(() => deriveApprovalPreview('Bash', null)).not.toThrow()
    expect(deriveApprovalPreview('Bash', null)).toBeNull()
    expect(deriveApprovalPreview('Bash', [1, 2])).toBeNull()
    expect(deriveApprovalPreview('Edit', 42)).toBeNull()
    expect(deriveApprovalPreview('Bash', 'ls -la')).toBeNull()
  })
})