/**
 * Human-facing `/approve` command for DeepSeek Harness.
 *
 * `/approve <change-id> design|plan` is the only writer of
 * `openspec/changes/<id>/approval.md` (D-1). The command checks the upstream
 * artifacts, asks the owner through `userQuestions.ask` (D-12), and only then
 * merges the new section into the existing file. A missing user-questions
 * service refuses instead of writing, so no model tool can approve itself.
 *
 * The repository root is resolved per invocation from the receiving agent's
 * session (`workingDirectory.get(agent.session)`, T3.1) — the registration
 * itself carries no root, because the command runs against whatever agent
 * invoked it.
 *
 * Mirrors `command-role.js`: object-form `commands.register`, the same
 * `{ kind, text }` result shape.
 */

import { mkdirSync, readFileSync, readdirSync, statSync, writeFileSync } from 'node:fs'
import { dirname, join, relative, resolve } from 'node:path'
import {
  APPROVAL_FILE,
  CHANGE_DIR,
  PLANS_DIR,
  extractSpec,
  hasDesignApproval,
  hashPlan,
  parseApproval,
  resolveChangeFromSpec,
  serializeApproval,
} from './lib/gates.js'

const USAGE = [
  'Usage: /approve <change-id> design|plan',
  '  design — record the owner approval of the change design',
  '  plan   — record the owner approval of the plan whose **Spec:** is <change-id>',
].join('\n')

const DESIGN_ARTIFACTS = ['proposal.md', 'design.md', 'builder-check.md']
const APPROVE_LABEL = 'Approve'
const CANCEL_LABEL = 'Cancel'
/** Change ids are directory names: keep them one safe path segment. */
const CHANGE_ID = /^[A-Za-z0-9][A-Za-z0-9._-]*$/u

function isFile(path) {
  try {
    return statSync(path).isFile()
  } catch {
    return false
  }
}

function readText(path) {
  try {
    return readFileSync(path, 'utf8')
  } catch {
    return null
  }
}

/** Session working directory of the invoking agent; process.cwd() fallback. */
function currentDirectory(workingDirectory, agent) {
  try {
    const cwd = workingDirectory?.get?.(agent?.session)
    if (typeof cwd === 'string' && cwd !== '') return cwd
  } catch {
    // Fall through to the process directory.
  }
  return process.cwd()
}

function refusal(text) {
  return { kind: 'error', text: `Refused: ${text}` }
}

function usage(text) {
  return { kind: 'error', text: `${text}\n${USAGE}` }
}

/**
 * Read the answer of `userQuestions.ask`.
 *
 * The DSH UserQuestionService resolves to `{ answers: [{ id, selected }] }`;
 * the plan/brief contract also allows `{ approved }` / `{ confirmed }` (and a
 * bare `true`) so the command stays testable without the runtime. Anything
 * else — a skipped question, a cancel, a timeout, null — is not an approval.
 */
function isApproved(answer) {
  if (answer === true) return true
  if (answer === null || typeof answer !== 'object') return false

  const flag = answer.approved ?? answer.confirmed
  if (flag !== undefined) return Boolean(flag)

  const items = Array.isArray(answer.answers) ? answer.answers : []
  return items.some(
    (item) => item !== null && typeof item === 'object' && Array.isArray(item.selected) && item.selected.includes(APPROVE_LABEL),
  )
}

/**
 * Ask the owner and return `{ ok: true }` or a refusal `{ ok: false, text }`.
 * The detail shows exactly what is being approved; the answer is never
 * inferred from the absence of an error.
 */
async function askOwner(userQuestions, { changeId, kind, detail, agent, signal }) {
  if (typeof userQuestions?.ask !== 'function') {
    return { ok: false, text: 'userQuestions service unavailable; /approve requires it' }
  }

  const request = {
    questions: [
      {
        id: `approve-${kind}`,
        header: 'Approve',
        question: `Approve ${changeId} ${kind}?`,
        detail,
        options: [
          {
            label: APPROVE_LABEL,
            description: `Write the ${kind} approval to openspec/changes/${changeId}/approval.md.`,
          },
          { label: CANCEL_LABEL, description: 'Write nothing.' },
        ],
      },
    ],
  }
  if (agent !== undefined) request.agent = agent
  if (signal !== undefined) request.signal = signal

  let answer
  try {
    answer = await userQuestions.ask(request)
  } catch (error) {
    return { ok: false, text: `userQuestions failed: ${String(error?.message ?? error)}` }
  }

  return isApproved(answer) ? { ok: true } : { ok: false, text: 'not confirmed' }
}

/** Merge one section into approval.md, leaving every other section as is. */
function writeApproval(root, changeId, mutate) {
  const path = join(root, CHANGE_DIR, changeId, APPROVAL_FILE)
  const next = mutate(parseApproval(readText(path)))
  mkdirSync(dirname(path), { recursive: true })
  writeFileSync(path, serializeApproval(next), 'utf8')
  return path
}

/** Existing plans under docs/superpowers/plans/ whose **Spec:** is `<id>`. */
function plansForChange(root, changeId) {
  const plansDir = join(root, PLANS_DIR)
  let names
  try {
    names = readdirSync(plansDir)
  } catch {
    return []
  }

  const found = []
  for (const name of [...names].sort()) {
    if (!name.endsWith('.md')) continue
    const path = join(plansDir, name)
    if (!isFile(path)) continue
    const content = readText(path)
    if (content === null) continue
    if (resolveChangeFromSpec(extractSpec(content)) === changeId) found.push(path)
  }
  return found
}

function approvalText(root, path) {
  return relative(root, path).split('\\').join('/')
}

async function approveDesign({ root, changeId, userQuestions, agent, signal }) {
  const changeDir = join(root, CHANGE_DIR, changeId)
  const missing = DESIGN_ARTIFACTS.filter((name) => !isFile(join(changeDir, name)))
  if (missing.length > 0) {
    const listed = missing.map((name) => `openspec/changes/${changeId}/${name}`).join(', ')
    return refusal(`design approval requires the change artifacts; missing: ${listed}.`)
  }

  const asked = await askOwner(userQuestions, {
    changeId,
    kind: 'design',
    detail: `Change: openspec/changes/${changeId} (proposal.md, design.md, builder-check.md).`,
    agent,
    signal,
  })
  if (!asked.ok) return refusal(asked.text)

  const at = new Date().toISOString()
  const path = writeApproval(root, changeId, (approval) => ({
    ...approval,
    design: { by: 'owner', at },
  }))
  return {
    kind: 'success',
    text: `Approved ${changeId} design at ${at}; wrote ${approvalText(root, path)}.`,
  }
}

async function approvePlan({ root, changeId, userQuestions, agent, signal }) {
  const approval = parseApproval(readText(join(root, CHANGE_DIR, changeId, APPROVAL_FILE)))
  if (!hasDesignApproval(approval)) {
    return refusal(`design not approved; run /approve ${changeId} design`)
  }

  const plans = plansForChange(root, changeId)
  if (plans.length === 0) {
    return refusal(
      `no plan for ${changeId} found under ${PLANS_DIR.split('\\').join('/')}/ with **Spec:** openspec/changes/${changeId}.`,
    )
  }
  if (plans.length > 1) {
    const listed = plans.map((path) => approvalText(root, path)).join(', ')
    return refusal(`several plans reference ${changeId}: ${listed}. Keep exactly one.`)
  }

  const [planPath] = plans
  const sha256 = hashPlan(planPath)
  if (sha256 === '') {
    return refusal(`cannot read plan ${approvalText(root, planPath)}.`)
  }

  const asked = await askOwner(userQuestions, {
    changeId,
    kind: 'plan',
    detail: `Plan: ${approvalText(root, planPath)} (sha256 ${sha256}).`,
    agent,
    signal,
  })
  if (!asked.ok) return refusal(asked.text)

  const at = new Date().toISOString()
  const path = writeApproval(root, changeId, (current) => ({
    ...current,
    plan: { by: 'owner', at, sha256 },
  }))
  return {
    kind: 'success',
    text: `Approved ${changeId} plan at ${at} (sha256 ${sha256}); wrote ${approvalText(root, path)}.`,
  }
}

export function registerApproveCommand({ commands, userQuestions, workingDirectory, logger }) {
  commands.register({
    name: 'approve',
    description: 'Утвердить design или plan change (единственный писатель approval.md)',
    input: { hint: '<change-id> design|plan' },
    handler: async ({ agent, rawInput, signal } = {}) => {
      const parts =
        typeof rawInput === 'string' ? rawInput.trim().split(/\s+/u).filter((part) => part !== '') : []

      if (parts.length !== 2) {
        return usage('Missing arguments: expected <change-id> design|plan.')
      }

      const [changeId, kind] = parts
      if (!CHANGE_ID.test(changeId)) {
        return usage(`Invalid change id "${changeId}".`)
      }
      if (kind !== 'design' && kind !== 'plan') {
        return usage(`Unknown kind "${kind}".`)
      }

      const root = resolve(currentDirectory(workingDirectory, agent))
      try {
        if (kind === 'design') {
          return await approveDesign({ root, changeId, userQuestions, agent, signal })
        }
        return await approvePlan({ root, changeId, userQuestions, agent, signal })
      } catch (error) {
        logger?.warn?.('[dsh-harness] /approve failed: %s', error?.message ?? error)
        return refusal(`/approve failed: ${String(error?.message ?? error)}`)
      }
    },
  })
}