// Application core of generate-meeting-document.
//
// The flow (claim -> provider -> commit, with a failure marker on every exit
// after a successful claim) depends only on the ports below, so it can be
// exercised without Supabase, Anthropic or an HTTP runtime. index.ts is the
// adapter that wires real clients into these ports and turns the result into a
// Response.
//
// Quota: the claim RPC reserves one unit of the user's LLM allowance through
// the shared reserve_llm_quota lease (migration 20260929020000), the same
// ledger llm-proxy uses, so a running document and a chat request can never
// both take the last unit. commit settles the lease; markFailed releases it.
// Every path that leaves a claimed request unfinished must therefore call
// markFailed so the unit is returned immediately instead of waiting for the
// 10 minute lease to expire. commit can still answer generation_quota_exceeded
// when the lease expired (or the claim predates the lease) and the allowance
// is spent by then; that maps to markFailed('quota_exceeded') + 429.

import { buildMeetingDocumentSystemPrompt } from '../_shared/generative-ai-safety.ts'
import {
  type GenerateMeetingDocumentRequest,
  parseProviderDocumentResult,
  type ProviderDocumentResult,
} from '../_shared/meeting-document-contract.ts'

export type GenerationFailureCode =
  | 'provider_timeout'
  | 'provider_request_failed'
  | 'provider_invalid_response'
  | 'quota_exceeded'
  | 'commit_failed'

export interface DatabaseError {
  code?: string
  message?: string
}

export interface RpcResult {
  data: unknown
  error: DatabaseError | null
}

export interface GenerationHttpResult {
  status: number
  body: Record<string, unknown>
}

export interface ClaimResult {
  claimed: boolean
  status: 'processing' | 'succeeded' | 'failed'
  documentId: string | null
  meetingTitle: string
  documentTitle: string
  templateType: string
  systemPrompt: string | null
  transcript: string | null
  model: string
}

export interface ProviderRequest {
  model: string
  max_tokens: number
  system: string
  messages: Array<{ role: 'user'; content: string }>
  stream: false
}

/** Outcome of one provider call, already classified by the adapter. */
export type ProviderOutcome =
  | { kind: 'ok'; body: unknown }
  | { kind: 'timeout' }
  | { kind: 'network_error' }
  | { kind: 'http_error'; status: number }

/** Persistence port: the four RPC/table operations the flow needs. */
export interface MeetingDocumentStore {
  claim(actorId: string, request: GenerateMeetingDocumentRequest): Promise<RpcResult>
  markFailed(actorId: string, idempotencyKey: string, code: GenerationFailureCode): Promise<DatabaseError | null>
  commit(
    actorId: string,
    idempotencyKey: string,
    result: ProviderDocumentResult,
    latencyMs: number,
  ): Promise<RpcResult>
  findDocument(actorId: string, documentId: string): Promise<RpcResult>
}

/** Provider port: sends one document request and classifies the transport outcome. */
export interface MeetingDocumentProvider {
  generate(request: ProviderRequest): Promise<ProviderOutcome>
}

export type GenerationLogger = (message: string, context?: Record<string, unknown>) => void

export interface GenerationDeps {
  store: MeetingDocumentStore
  provider: MeetingDocumentProvider
  now: () => number
  log: GenerationLogger
}

export const PROVIDER_MAX_TOKENS = 4096

function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === 'object' && value !== null && !Array.isArray(value)
}

function result(status: number, body: Record<string, unknown>): GenerationHttpResult {
  return { status, body }
}

export function parseClaim(value: unknown): ClaimResult | null {
  if (!isRecord(value)) return null
  if (
    typeof value.claimed !== 'boolean'
    || !['processing', 'succeeded', 'failed'].includes(String(value.status))
    || (value.documentId !== null && typeof value.documentId !== 'string')
    || typeof value.meetingTitle !== 'string'
    || typeof value.documentTitle !== 'string'
    || typeof value.templateType !== 'string'
    || (value.systemPrompt !== null && typeof value.systemPrompt !== 'string')
    || (value.transcript !== null && typeof value.transcript !== 'string')
    || typeof value.model !== 'string'
  ) {
    return null
  }
  return value as unknown as ClaimResult
}

export function isQuotaExceeded(error: DatabaseError | null): boolean {
  return error?.message?.includes('generation_quota_exceeded') === true
}

export function mapDatabaseError(error: DatabaseError | null, log: GenerationLogger): GenerationHttpResult {
  const code = error?.code ?? ''
  if (code === '42501') return result(403, { error: 'forbidden' })
  if (code === 'P0002') return result(404, { error: 'not_found' })
  if (code === '22023') return result(400, { error: 'invalid_request' })
  if (isQuotaExceeded(error)) return result(429, { error: 'quota_exceeded' })
  log('meeting document database operation failed', { code: code || 'unknown' })
  return result(500, { error: 'internal_error' })
}

export function buildProviderRequest(
  claim: ClaimResult & { systemPrompt: string; transcript: string },
): ProviderRequest {
  return {
    model: claim.model,
    max_tokens: PROVIDER_MAX_TOKENS,
    system: buildMeetingDocumentSystemPrompt(claim.systemPrompt),
    messages: [{
      role: 'user',
      content: `회의 제목: ${claim.meetingTitle}\n\n전사록:\n${claim.transcript}`,
    }],
    stream: false,
  }
}

async function replayClaim(
  actorId: string,
  claim: ClaimResult,
  deps: GenerationDeps,
): Promise<GenerationHttpResult> {
  if (claim.status === 'succeeded' && claim.documentId !== null) {
    const { data: document, error } = await deps.store.findDocument(actorId, claim.documentId)
    if (error !== null || document === null || document === undefined) {
      deps.log('idempotent meeting document lookup failed', { code: error?.code ?? 'missing' })
      return result(500, { error: 'internal_error' })
    }
    return result(200, { document, idempotent: true })
  }
  return result(409, {
    error: claim.status === 'processing' ? 'generation_in_progress' : 'generation_failed',
  })
}

async function runClaimedGeneration(
  actorId: string,
  request: GenerateMeetingDocumentRequest,
  claim: ClaimResult & { systemPrompt: string; transcript: string },
  deps: GenerationDeps,
  markFailed: (code: GenerationFailureCode) => Promise<void>,
): Promise<GenerationHttpResult> {
  const startedAt = deps.now()
  const outcome = await deps.provider.generate(buildProviderRequest(claim))

  if (outcome.kind === 'timeout') {
    await markFailed('provider_timeout')
    return result(504, { error: 'provider_timeout' })
  }
  if (outcome.kind === 'network_error') {
    await markFailed('provider_request_failed')
    return result(502, { error: 'provider_request_failed' })
  }
  if (outcome.kind === 'http_error') {
    deps.log('meeting document provider request failed', { status: outcome.status })
    await markFailed('provider_request_failed')
    return result(502, { error: 'provider_request_failed' })
  }

  const providerResult = parseProviderDocumentResult(outcome.body)
  if (providerResult === null) {
    deps.log('meeting document provider returned an invalid response shape')
    await markFailed('provider_invalid_response')
    return result(502, { error: 'provider_invalid_response' })
  }

  const { data: commitData, error: commitError } = await deps.store.commit(
    actorId,
    request.idempotencyKey,
    providerResult,
    Math.max(0, deps.now() - startedAt),
  )
  if (commitError !== null) {
    const quotaExceeded = isQuotaExceeded(commitError)
    await markFailed(quotaExceeded ? 'quota_exceeded' : 'commit_failed')
    if (quotaExceeded) return result(429, { error: 'quota_exceeded' })
    deps.log('meeting document atomic commit failed', { code: commitError.code ?? 'unknown' })
    return result(500, { error: 'commit_failed' })
  }
  if (!isRecord(commitData) || !isRecord(commitData.document)) {
    deps.log('meeting document commit returned an invalid shape')
    return result(500, { error: 'internal_error' })
  }

  return result(200, {
    document: commitData.document,
    idempotent: commitData.idempotent === true,
  })
}

/**
 * Claims the request, calls the provider and commits the document.
 * Throws only for unexpected adapter failures; a claimed request is marked
 * failed before such an error propagates, so its quota unit is released.
 */
export async function generateMeetingDocument(
  actorId: string,
  request: GenerateMeetingDocumentRequest,
  deps: GenerationDeps,
): Promise<GenerationHttpResult> {
  const markFailed = async (code: GenerationFailureCode): Promise<void> => {
    try {
      const error = await deps.store.markFailed(actorId, request.idempotencyKey, code)
      if (error !== null) {
        deps.log('meeting document failure marker failed', { code: error.code ?? 'unknown' })
      }
    } catch {
      deps.log('meeting document failure marker failed', { code: 'exception' })
    }
  }

  const { data: claimData, error: claimError } = await deps.store.claim(actorId, request)
  if (claimError !== null) return mapDatabaseError(claimError, deps.log)

  const claim = parseClaim(claimData)
  if (claim === null) {
    deps.log('meeting document claim returned an invalid shape')
    return result(500, { error: 'internal_error' })
  }
  if (!claim.claimed) return await replayClaim(actorId, claim, deps)

  if (claim.systemPrompt === null || claim.transcript === null) {
    await markFailed('commit_failed')
    return result(500, { error: 'internal_error' })
  }
  const readyClaim = { ...claim, systemPrompt: claim.systemPrompt, transcript: claim.transcript }

  try {
    return await runClaimedGeneration(actorId, request, readyClaim, deps, markFailed)
  } catch (error) {
    // Release the in-flight quota unit held by this claim; the request is not
    // going to be committed. A no-op if commit already moved it out of
    // 'processing'.
    await markFailed('commit_failed')
    throw error
  }
}