import { strict as assert } from 'node:assert'
import { rm } from 'node:fs/promises'
import { join } from 'node:path'
import { test } from 'node:test'

import { RecallIndex } from '../lib/store.js'
import { makeStateDir } from './helpers.js'

const IDENTITY = { model: 'test-model', dimensions: 4, apiBase: 'http://stub' }

/** A chunk with a hand-written vector, so assertions are exact. */
function chunk(startLine, vector, symbol) {
  return {
    startLine,
    endLine: startLine + 2,
    ...(symbol === undefined ? {} : { symbol }),
    text: `line ${startLine}`,
    vec: Float32Array.from(vector),
  }
}

async function withIndex(t, work) {
  const dir = await makeStateDir()
  const index = new RecallIndex(join(dir, 'index.sqlite'))
  t.after(async () => {
    index.close()
    await rm(dir, { recursive: true, force: true })
  })
  index.open(IDENTITY)
  return work(index)
}

test('replaceFile round-trips chunks and their vectors', async (t) => {
  await withIndex(t, (index) => {
    index.replaceFile('a.ts', 'hash-a', 100, [chunk(1, [1, 0, 0, 0], 'alpha'), chunk(10, [0, 1, 0, 0], 'beta')])
    const stats = index.stats()
    assert.equal(stats.files, 1)
    assert.equal(stats.chunks, 2)

    const matrix = index.matrix()
    assert.equal(matrix.dimensions, 4)
    assert.equal(matrix.rows.length, 2)
    assert.deepEqual(Array.from(matrix.vectors.slice(0, 4)), [1, 0, 0, 0])
    assert.equal(matrix.rows[0].symbol, 'alpha')
    assert.equal(matrix.rows[0].path, 'a.ts')
  })
})

test('replacing a file drops its previous chunks rather than appending', async (t) => {
  await withIndex(t, (index) => {
    index.replaceFile('a.ts', 'hash-1', 10, [chunk(1, [1, 0, 0, 0])])
    index.replaceFile('a.ts', 'hash-2', 20, [chunk(1, [0, 1, 0, 0]), chunk(5, [0, 0, 1, 0])])
    assert.equal(index.stats().chunks, 2)
    assert.equal(index.fileHashes().get('a.ts'), 'hash-2')
  })
})

test('prune forgets files that disappeared from disk', async (t) => {
  await withIndex(t, (index) => {
    index.replaceFile('a.ts', 'ha', 1, [chunk(1, [1, 0, 0, 0])])
    index.replaceFile('b.ts', 'hb', 1, [chunk(1, [0, 1, 0, 0])])
    assert.equal(index.prune(['a.ts']), 1)
    assert.equal(index.stats().files, 1)
    assert.equal(index.matrix().rows[0].path, 'b.ts')
    assert.equal(index.prune([]), 0)
  })
})

test('changing the embedding model discards the index instead of mixing spaces', async (t) => {
  await withIndex(t, (index) => {
    index.replaceFile('a.ts', 'ha', 1, [chunk(1, [1, 0, 0, 0])])
    assert.equal(index.stats().chunks, 1)

    const outcome = index.recheck({ model: 'other-model', dimensions: 4, apiBase: 'http://stub' })
    assert.match(outcome.discarded, /embedding model changed/)
    assert.equal(index.stats().chunks, 0)
    assert.equal(index.stats().files, 0)
  })
})

test('changing the embedding width discards the index', async (t) => {
  await withIndex(t, (index) => {
    index.replaceFile('a.ts', 'ha', 1, [chunk(1, [1, 0, 0, 0])])
    const outcome = index.recheck({ model: 'test-model', dimensions: 8, apiBase: 'http://stub' })
    assert.match(outcome.discarded, /embedding width changed/)
    assert.equal(index.stats().chunks, 0)
  })
})

test('recheck is a no-op when nothing about the identity moved', async (t) => {
  await withIndex(t, (index) => {
    index.replaceFile('a.ts', 'ha', 1, [chunk(1, [1, 0, 0, 0])])
    assert.deepEqual(index.recheck(IDENTITY), {})
    assert.equal(index.stats().chunks, 1)
  })
})

test('a write invalidates the cached matrix', async (t) => {
  await withIndex(t, (index) => {
    index.replaceFile('a.ts', 'ha', 1, [chunk(1, [1, 0, 0, 0])])
    assert.equal(index.matrix().rows.length, 1)
    index.replaceFile('b.ts', 'hb', 1, [chunk(1, [0, 1, 0, 0])])
    assert.equal(index.matrix().rows.length, 2, 'the matrix must not serve a stale cache')
  })
})

test('an index with no chunks reports a zero-width matrix', async (t) => {
  await withIndex(t, (index) => {
    const matrix = index.matrix()
    assert.equal(matrix.rows.length, 0)
    assert.equal(matrix.dimensions, 0)
  })
})