'use strict'

// Git ops backing the coding rail + Codex-style review pane. Built on `simple-git`
// (a maintained wrapper around the system git binary — same git the rest of the
// app shells to, no native build) so we read structured status()/diffSummary()
// results instead of hand-parsing porcelain. Reads degrade to null/empty on a
// non-repo / remote backend; mutations reject so the renderer can toast.

const { execFile } = require('node:child_process')
const fs = require('node:fs/promises')
const path = require('node:path')

// `simple-git` is a pure-JS runtime dep that workspace dedup hoists into the
// repo-root node_modules.  Packaged builds set `files:` in package.json, which
// excludes node_modules from the asar, so the normal require() fails at launch
// (issue #52735: "Cannot find module 'simple-git'").  We ship the dep's
// closure under resources/native-deps/vendor/node_modules/ via extraResources
// + scripts/stage-native-deps.cjs, and resolve from there when the hoisted
// require() isn't reachable.  The `vendor/` nesting matters: electron-builder
// drops a node_modules dir at the root of an extraResources copy but keeps a
// nested one.  Dev mode never hits the fallback -- Node's normal lookup finds
// the hoisted copy.
let simpleGit
try {
  simpleGit = require('simple-git')
} catch {
  const resourcesPath = process.resourcesPath
  if (!resourcesPath) {
    throw new Error("git-review IPC: 'simple-git' not found and no resourcesPath to fall back to")
  }
  simpleGit = require(path.join(resourcesPath, 'native-deps', 'vendor', 'node_modules', 'simple-git'))
}

const { resolveRequestedPathForIpc } = require('./hardening.cjs')

const COMMIT_CONTEXT_DIFF_MAX_CHARS = 120_000
const COMMIT_CONTEXT_UNTRACKED_MAX = 80
const UNTRACKED_LINE_COUNT_CONCURRENCY = 16
const UNTRACKED_LINE_COUNT_MAX_BYTES = 1024 * 1024

// GUI-launched Electron apps on macOS inherit only a minimal PATH (no
// /opt/homebrew/bin or /usr/local/bin), so `gh` — and the `git` gh shells out
// to — aren't found. Augment PATH with the resolved gh dir + the common
// package-manager bins so gh runs the same way it does in a terminal.
function ghEnv(ghBin) {
  const extra = [ghBin ? path.dirname(ghBin) : '', '/opt/homebrew/bin', '/usr/local/bin', '/usr/bin'].filter(
    dir => dir && dir !== '.'
  )

  return { ...process.env, PATH: [...extra, process.env.PATH].filter(Boolean).join(path.delimiter) }
}

// Run the `gh` CLI in a repo. Resolves { ok, stdout } so callers branch on
// availability/auth without a throw. gh missing/unauthed → ok:false.
function runGh(args, cwd, ghBin) {
  return new Promise(resolve => {
    execFile(
      ghBin || 'gh',
      args,
      { cwd, env: ghEnv(ghBin), windowsHide: true, timeout: 30_000, maxBuffer: 8 * 1024 * 1024 },
      (err, stdout) => resolve({ ok: !err, stdout: String(stdout || '') })
    )
  })
}

function gitFor(cwd, gitBin) {
  return simpleGit({ baseDir: cwd, binary: gitBin || 'git', maxConcurrentProcesses: 4, trimmed: false })
}

// simple-git reports renames as `old => new` (and `dir/{old => new}/f`); resolve
// to the NEW path so the row addresses the real file for diff/stage.
function resolveRenamePath(raw) {
  const path = String(raw || '').trim()

  if (!path.includes(' => ')) {
    return path
  }

  const brace = path.match(/^(.*)\{(.*) => (.*)\}(.*)$/)

  if (brace) {
    const [, prefix, , to, suffix] = brace

    return `${prefix}${to}${suffix}`.replace(/\/{2,}/g, '/')
  }

  return path.split(' => ').pop().trim()
}

// DiffResult.files → Map<path, {added, removed}> (binary files carry no line
// delta).
function countsByPath(summary) {
  const map = new Map()

  for (const file of summary.files) {
    map.set(resolveRenamePath(file.file), {
      added: file.binary ? 0 : file.insertions,
      removed: file.binary ? 0 : file.deletions
    })
  }

  return map
}

// Untracked files don't appear in diffSummary(); count insertions from disk so
// the review tree can show +N for new files (matches an all-add diff view).
// Insertions = line count: newline bytes, plus one for a final unterminated
// line. Binary (NUL byte) → 0, mirroring git numstat's "-".
async function untrackedInsertions(cwd, relPath) {
  try {
    const fullPath = path.join(cwd, relPath)
    const stat = await fs.stat(fullPath)

    if (!stat.isFile() || stat.size > UNTRACKED_LINE_COUNT_MAX_BYTES) {
      return 0
    }

    const buf = await fs.readFile(fullPath)

    if (buf.includes(0)) {
      return 0
    }

    let lines = 0

    for (const byte of buf) {
      if (byte === 10) {
        lines++
      }
    }

    return buf.length > 0 && buf[buf.length - 1] !== 10 ? lines + 1 : lines
  } catch {
    return 0
  }
}

function capText(text, maxChars, label = 'truncated') {
  const value = String(text || '')

  if (value.length <= maxChars) {
    return value
  }

  return `${value.slice(0, maxChars)}\n# ${label}: ${value.length - maxChars} chars omitted\n`
}

async function fillUntrackedCounts(cwd, files) {
  const pending = files.filter(file => file.status === '?' && file.added === 0 && file.removed === 0)

  for (let i = 0; i < pending.length; i += UNTRACKED_LINE_COUNT_CONCURRENCY) {
    await Promise.all(
      pending.slice(i, i + UNTRACKED_LINE_COUNT_CONCURRENCY).map(async file => {
        file.added = await untrackedInsertions(cwd, file.path)
      })
    )
  }
}

// Resolve the base ref for "all branch changes": merge-base with the remote
// default branch (origin/HEAD), falling back to common trunk names.
async function branchBase(git) {
  const candidates = []

  try {
    const head = (await git.revparse(['--abbrev-ref', 'origin/HEAD'])).trim()

    if (head) {
      candidates.push(head)
    }
  } catch {
    // No origin/HEAD configured.
  }

  candidates.push('origin/main', 'origin/master', 'main', 'master')

  for (const ref of candidates) {
    try {
      const base = (await git.raw(['merge-base', 'HEAD', ref])).trim()

      if (base) {
        return base
      }
    } catch {
      // Ref doesn't exist; try the next candidate.
    }
  }

  return null
}

// Resolve the repo's default branch NAME ("main" / "master" / …), preferring
// the remote's HEAD, then common local trunk names. Null when none is found
// (e.g. a fresh repo with only a feature branch). Used to offer "branch off the
// trunk" regardless of which branch you're currently on.
async function defaultBranchName(git) {
  try {
    const head = (await git.revparse(['--abbrev-ref', 'origin/HEAD'])).trim()

    // "origin/main" → "main"; skip the bare "origin/HEAD" placeholder.
    if (head && head !== 'origin/HEAD') {
      return head.replace(/^origin\//, '')
    }
  } catch {
    // No origin/HEAD configured.
  }

  // Prefer a local trunk, then a remote-only one (returns the clean name either
  // way) so "branch off main" works even before main is checked out locally.
  for (const ref of [
    'refs/heads/main',
    'refs/heads/master',
    'refs/remotes/origin/main',
    'refs/remotes/origin/master'
  ]) {
    try {
      await git.raw(['rev-parse', '--verify', '--quiet', ref])

      return ref.replace(/^refs\/(?:heads|remotes\/origin)\//, '')
    } catch {
      // Ref doesn't exist; try the next candidate.
    }
  }

  return null
}

// A status file's single-letter classification, preferring the staged (index)
// code over the worktree code; untracked wins (simple-git marks both '?').
function statusLetter(file) {
  if (file.index === '?' || file.working_dir === '?') {
    return '?'
  }

  const code = file.index && file.index !== ' ' ? file.index : file.working_dir

  return (code || 'M').toUpperCase()
}

const isStaged = file => Boolean(file.index && file.index !== ' ' && file.index !== '?')

async function reviewList(repoPath, scope, baseRef, gitBin) {
  let cwd

  try {
    cwd = resolveRequestedPathForIpc(repoPath, { purpose: 'Review list' })
  } catch {
    return { files: [], base: null }
  }

  const git = gitFor(cwd, gitBin)

  try {
    if (scope === 'branch' || scope === 'lastTurn') {
      const base = scope === 'branch' ? await branchBase(git) : baseRef

      if (!base) {
        return { files: [], base: null }
      }

      const range = scope === 'branch' ? `${base}...HEAD` : base
      const summary = await git.diffSummary([range])
      const files = summary.files.map(file => ({
        path: resolveRenamePath(file.file),
        added: file.binary ? 0 : file.insertions,
        removed: file.binary ? 0 : file.deletions,
        status: 'M',
        staged: false
      }))

      // "Last turn" also surfaces files created since the baseline (untracked).
      if (scope === 'lastTurn') {
        const status = await git.status()

        for (const path of status.not_added) {
          if (!files.some(f => f.path === path)) {
            files.push({ path, added: 0, removed: 0, status: '?', staged: false })
          }
        }
      }

      files.sort((a, b) => a.path.localeCompare(b.path))
      await fillUntrackedCounts(cwd, files)

      return { files, base }
    }

    // Default: uncommitted (staged + unstaged + untracked), one row per path.
    const [status, staged, unstaged] = await Promise.all([
      git.status(),
      git.diffSummary(['--cached']),
      git.diffSummary([])
    ])
    const stagedCounts = countsByPath(staged)
    const unstagedCounts = countsByPath(unstaged)

    const files = status.files.map(file => {
      const filePath = resolveRenamePath(file.path)
      const sc = stagedCounts.get(filePath) || { added: 0, removed: 0 }
      const uc = unstagedCounts.get(filePath) || { added: 0, removed: 0 }

      return {
        path: filePath,
        added: sc.added + uc.added,
        removed: sc.removed + uc.removed,
        status: statusLetter(file),
        staged: isStaged(file)
      }
    })

    files.sort((a, b) => a.path.localeCompare(b.path))
    await fillUntrackedCounts(cwd, files)

    return { files, base: null }
  } catch {
    return { files: [], base: null }
  }
}

async function reviewDiff(repoPath, filePath, scope, baseRef, staged, gitBin) {
  let cwd

  try {
    cwd = resolveRequestedPathForIpc(repoPath, { purpose: 'Review diff' })
  } catch {
    return ''
  }

  const git = gitFor(cwd, gitBin)
  const safe = args => git.diff(args).catch(() => '')

  if (scope === 'branch') {
    const base = await branchBase(git)

    return base ? safe([`${base}...HEAD`, '--', filePath]) : ''
  }

  if (scope === 'lastTurn') {
    return baseRef ? safe([baseRef, '--', filePath]) : ''
  }

  if (staged) {
    return safe(['--cached', '--', filePath])
  }

  const worktree = await safe(['--', filePath])

  if (worktree.trim()) {
    return worktree
  }

  // Untracked file: no worktree diff exists, so synthesize an all-add diff via
  // --no-index (exits non-zero by design when files differ, so go around
  // simple-git's reject-on-nonzero with a raw execFile).
  return new Promise(resolve => {
    execFile(
      gitBin || 'git',
      ['diff', '--no-index', '--', '/dev/null', filePath],
      { cwd, windowsHide: true, timeout: 30_000, maxBuffer: 32 * 1024 * 1024 },
      (_err, stdout) => resolve(String(stdout || ''))
    )
  })
}

// Working-tree-vs-HEAD diff for ONE file — the "what changed since the last
// commit" view used by the file preview. Unlike reviewDiff this never synthesizes
// a full-add for a clean tracked file (so a pristine file shows no diff); it only
// all-adds a genuinely untracked file.
async function fileDiffVsHead(repoPath, filePath, gitBin) {
  let cwd

  try {
    cwd = resolveRequestedPathForIpc(repoPath, { purpose: 'File diff' })
  } catch {
    return ''
  }

  const git = gitFor(cwd, gitBin)
  const head = await git.diff(['HEAD', '--', filePath]).catch(() => '')

  if (head.trim()) {
    return head
  }

  // No tracked changes vs HEAD. Only synthesize an all-add diff for a file git
  // doesn't know yet; a clean tracked file must return empty.
  const status = await git.raw(['status', '--porcelain', '--', filePath]).catch(() => '')

  if (!status.trim().startsWith('??')) {
    return ''
  }

  return new Promise(resolve => {
    execFile(
      gitBin || 'git',
      ['diff', '--no-index', '--', '/dev/null', filePath],
      { cwd, windowsHide: true, timeout: 30_000, maxBuffer: 32 * 1024 * 1024 },
      (_err, stdout) => resolve(String(stdout || ''))
    )
  })
}

async function reviewStage(repoPath, filePath, gitBin) {
  const cwd = resolveRequestedPathForIpc(repoPath, { purpose: 'Review stage' })

  await gitFor(cwd, gitBin).raw(filePath ? ['add', '--', filePath] : ['add', '-A'])

  return { ok: true }
}

async function reviewUnstage(repoPath, filePath, gitBin) {
  const cwd = resolveRequestedPathForIpc(repoPath, { purpose: 'Review unstage' })

  await gitFor(cwd, gitBin).raw(filePath ? ['reset', '-q', 'HEAD', '--', filePath] : ['reset', '-q', 'HEAD'])

  return { ok: true }
}

// Discard changes back to the committed state. Destructive — the renderer
// confirms first. Restores tracked files and removes untracked ones.
async function reviewRevert(repoPath, filePath, gitBin) {
  const cwd = resolveRequestedPathForIpc(repoPath, { purpose: 'Review revert' })
  const git = gitFor(cwd, gitBin)

  if (filePath) {
    await git.raw(['checkout', 'HEAD', '--', filePath]).catch(() => undefined)
    await git.raw(['clean', '-fd', '--', filePath]).catch(() => undefined)
  } else {
    await git.raw(['checkout', 'HEAD', '--', '.']).catch(() => undefined)
    await git.raw(['clean', '-fd']).catch(() => undefined)
  }

  return { ok: true }
}

// Resolve a ref to a commit sha (captures the turn baseline for "Last turn").
async function reviewRevParse(repoPath, ref, gitBin) {
  let cwd

  try {
    cwd = resolveRequestedPathForIpc(repoPath, { purpose: 'Review rev-parse' })
  } catch {
    return null
  }

  try {
    return (await gitFor(cwd, gitBin).revparse([ref || 'HEAD'])).trim() || null
  } catch {
    return null
  }
}

// Commit the working tree. Mirrors VS Code: if nothing is staged, stage
// everything first ("commit all"), then commit. Optionally push afterward,
// setting upstream on the first push.
async function reviewCommit(repoPath, message, push, gitBin) {
  const cwd = resolveRequestedPathForIpc(repoPath, { purpose: 'Review commit' })
  const git = gitFor(cwd, gitBin)
  const status = await git.status()

  if (status.staged.length === 0) {
    await git.raw(['add', '-A'])
  }

  await git.commit(message)

  if (push) {
    const fresh = await git.status()

    if (fresh.tracking) {
      await git.push()
    } else if (fresh.current) {
      await git.raw(['push', '-u', 'origin', fresh.current])
    }
  }

  return { ok: true }
}

// Gather the context the model needs to draft a commit message: the diff of
// what *will* be committed (staged when anything is staged, else everything
// vs HEAD — mirroring reviewCommit's "stage all when nothing staged" rule),
// the names of untracked files (which carry no diff), and recent commit
// subjects for style. Diff is capped so the payload stays bounded. Reads only.
async function reviewCommitContext(repoPath, gitBin) {
  let cwd

  try {
    cwd = resolveRequestedPathForIpc(repoPath, { purpose: 'Review commit context' })
  } catch {
    return { diff: '', recent: '' }
  }

  const git = gitFor(cwd, gitBin)
  const safe = args => git.diff(args).catch(() => '')

  let status
  try {
    status = await git.status()
  } catch {
    return { diff: '', recent: '' }
  }

  // What will land: staged changes if any, otherwise all tracked changes vs HEAD.
  let diff = capText(
    status.staged.length > 0 ? await safe(['--cached']) : await safe(['HEAD']),
    COMMIT_CONTEXT_DIFF_MAX_CHARS,
    'diff truncated for commit-message generation'
  )

  // Untracked files have no diff — list them so new files aren't invisible.
  const untracked = status.not_added || []
  if (untracked.length > 0) {
    const visible = untracked.slice(0, COMMIT_CONTEXT_UNTRACKED_MAX)
    const omitted = untracked.length - visible.length
    const note =
      `\n# New (untracked) files:\n${visible.map(p => `#   ${p}`).join('\n')}\n` +
      (omitted > 0 ? `#   ... ${omitted} more omitted\n` : '')

    diff = diff ? `${diff}${note}` : note
  }

  const recent = await git.raw(['log', '-n', '10', '--pretty=format:%s']).catch(() => '')

  return { diff: diff || '', recent: String(recent || '').trim() }
}

async function reviewPush(repoPath, gitBin) {
  const cwd = resolveRequestedPathForIpc(repoPath, { purpose: 'Review push' })
  const git = gitFor(cwd, gitBin)
  const status = await git.status()

  if (status.tracking) {
    await git.push()
  } else if (status.current) {
    await git.raw(['push', '-u', 'origin', status.current])
  }

  return { ok: true }
}

// gh availability + auth + whether this branch already has a PR. Reads only;
// drives the PR button's enabled/label state. `ghReady` is false when gh is
// missing OR not authenticated — either way the PR action can't run.
async function reviewShipInfo(repoPath, ghBin) {
  let cwd

  try {
    cwd = resolveRequestedPathForIpc(repoPath, { purpose: 'Review ship info' })
  } catch {
    return { ghReady: false, pr: null }
  }

  const auth = await runGh(['auth', 'status'], cwd, ghBin)

  if (!auth.ok) {
    return { ghReady: false, pr: null }
  }

  const view = await runGh(['pr', 'view', '--json', 'url,state,number'], cwd, ghBin)

  if (!view.ok) {
    // gh exits non-zero when no PR exists for the branch — that's not an error.
    return { ghReady: true, pr: null }
  }

  try {
    const pr = JSON.parse(view.stdout)

    return { ghReady: true, pr: pr && pr.url ? { url: pr.url, state: pr.state, number: pr.number } : null }
  } catch {
    return { ghReady: true, pr: null }
  }
}

// Create a PR for the current branch (pushing first so gh has a remote ref),
// letting gh fill title/body from the commits. Returns the new PR url.
async function reviewCreatePr(repoPath, gitBin, ghBin) {
  const cwd = resolveRequestedPathForIpc(repoPath, { purpose: 'Review create PR' })

  await reviewPush(repoPath, gitBin).catch(() => undefined)

  const created = await runGh(['pr', 'create', '--fill'], cwd, ghBin)

  if (!created.ok) {
    throw new Error('gh pr create failed (is gh installed and authenticated?)')
  }

  const url = created.stdout.trim().split('\n').filter(Boolean).pop() || ''

  return { url }
}

// Compact working-tree status for the composer coding rail: branch, ahead/behind,
// per-state change counts, +/- vs HEAD, and a capped changed-file list.
async function repoStatus(repoPath, gitBin) {
  let cwd

  try {
    cwd = resolveRequestedPathForIpc(repoPath, { purpose: 'Repo status' })
  } catch {
    return null
  }

  // Session cwds can point at a deleted worktree for a moment (or forever in a
  // stale row). simple-git throws at construction time on a missing baseDir, so
  // fail soft and hide the coding rail instead of spamming IPC handler errors.
  try {
    const stat = await fs.stat(cwd)
    if (!stat.isDirectory()) {
      return null
    }
  } catch {
    return null
  }

  let git
  try {
    git = gitFor(cwd, gitBin)
  } catch {
    return null
  }
  let status

  try {
    status = await git.status()
  } catch {
    // Not a repo / git unavailable / remote backend.
    return null
  }

  const detached = typeof status.detached === 'boolean' ? status.detached : !status.current
  const files = status.files.map(file => ({
    path: file.path,
    staged: isStaged(file),
    unstaged: Boolean(file.working_dir && file.working_dir !== ' ' && file.working_dir !== '?'),
    untracked: file.index === '?' || file.working_dir === '?',
    conflicted: file.index === 'U' || file.working_dir === 'U'
  }))

  const result = {
    branch: detached ? null : status.current || null,
    defaultBranch: await defaultBranchName(git),
    detached,
    ahead: status.ahead || 0,
    behind: status.behind || 0,
    staged: files.filter(f => f.staged).length,
    unstaged: files.filter(f => f.unstaged).length,
    untracked: status.not_added.length,
    conflicted: status.conflicted.length,
    changed: files.length,
    added: 0,
    removed: 0,
    files: files.slice(0, 200)
  }

  // +/- vs HEAD (staged + unstaged tracked changes). No HEAD yet → leave 0.
  try {
    const summary = await git.diffSummary(['HEAD'])
    result.added = summary.insertions
    result.removed = summary.deletions
  } catch {
    // No commits yet.
  }

  // `git diff HEAD` ignores untracked files, so a turn that only creates new
  // files (the common case — a fresh module, a demo dir) showed +0 in the rail
  // while the review pane counted them. Fold untracked insertions into `added`
  // so the rail matches reality. Bounded (size cap + concurrency) like the
  // review tree; only the capped file slice is counted so a huge untracked tree
  // can't stall the probe.
  try {
    const untracked = status.not_added.slice(0, 500)
    for (let i = 0; i < untracked.length; i += UNTRACKED_LINE_COUNT_CONCURRENCY) {
      const batch = await Promise.all(
        untracked.slice(i, i + UNTRACKED_LINE_COUNT_CONCURRENCY).map(path => untrackedInsertions(cwd, path))
      )
      result.added += batch.reduce((sum, n) => sum + n, 0)
    }
  } catch {
    // Best-effort: a probe failure just leaves untracked lines uncounted.
  }

  return result
}

module.exports = {
  branchBase,
  fileDiffVsHead,
  repoStatus,
  resolveRenamePath,
  reviewCommit,
  reviewCommitContext,
  reviewCreatePr,
  reviewDiff,
  reviewList,
  reviewPush,
  reviewRevParse,
  reviewRevert,
  reviewShipInfo,
  reviewStage,
  reviewUnstage
}