import "server-only";

import {
  LONGFORM_APPENDIX_TABLE,
  nextLongformAppendixState,
  parseLongformAppendixRow,
  type LongformAppendixRow,
} from "./personal-report-longform-appendix";
import { buildLongformBirthPayload, utcToday } from "./personal-report-longform-birth";
import { buildLongformCoverDocument } from "./personal-report-longform-cover";
import type { GeneratePersonalReportResult } from "./personal-report-generation";
import type { PersonalReportRecord } from "./personal-report-service-core";
import type { ReportDocumentV2 } from "./personal-report-contract";

const APPENDIX_SELECT =
  "report_id,user_id,request_id,status,markdown,content_sha256,attempt_count,last_error_code";
const DEFAULT_API_BASE = "http://127.0.0.1:5200";
const ENGINE_TIMEOUT_MS = 180_000;

export class LongformGenerateError extends Error {
  readonly name = "LongformGenerateError";

  constructor(
    readonly code: "calculation_unavailable" | "report_schema_invalid" | "birth_time_not_usable",
    readonly retryable: boolean,
    message?: string,
  ) {
    super(message ?? code);
  }
}

type JsonRecord = Record<string, unknown>;

export type AppendixClient = {
  from(table: string): {
    select(columns: string): {
      eq(column: string, value: unknown): AppendixFilter;
    };
    upsert(
      row: JsonRecord,
      options?: { onConflict?: string },
    ): PromiseLike<{ error: { message?: string } | null }>;
  };
};

type AppendixFilter = {
  eq(column: string, value: unknown): AppendixFilter;
  maybeSingle(): PromiseLike<{ data: unknown; error: { message?: string } | null }>;
};

export type LongformGenerateDeps = Readonly<{
  report: PersonalReportRecord;
  profile: unknown;
  candidateRange: Readonly<{ startTime: string; endTime: string }> | null;
  admin: AppendixClient;
  displayName: string;
  birthTimeStatus: ReportDocumentV2["subject"]["birthTimeStatus"];
  apiBase?: string;
  fetchImpl?: typeof fetch;
  now?: () => Date;
  signal?: AbortSignal;
}>;

function record(value: unknown): JsonRecord | null {
  return value !== null && typeof value === "object" && !Array.isArray(value)
    ? value as JsonRecord
    : null;
}

function text(value: unknown): string | null {
  if (typeof value !== "string") return null;
  const trimmed = value.trim();
  return trimmed.length > 0 ? trimmed : null;
}

export async function readOwnedLongformAppendix(
  client: AppendixClient,
  reportId: string,
  userId: string,
): Promise<LongformAppendixRow | null> {
  const result = await client
    .from(LONGFORM_APPENDIX_TABLE)
    .select(APPENDIX_SELECT)
    .eq("report_id", reportId)
    .eq("user_id", userId)
    .maybeSingle();
  if (result.error) return null;
  return parseLongformAppendixRow(result.data);
}

export async function persistLongformAppendix(input: Readonly<{
  admin: AppendixClient;
  reportId: string;
  userId: string;
  requestId: string;
  current: LongformAppendixRow | null;
  successMarkdown?: string | null;
  errorCode?: string | null;
}>): Promise<void> {
  const next = nextLongformAppendixState({
    current: input.current,
    successMarkdown: input.successMarkdown,
    errorCode: input.errorCode,
  });
  try {
    const result = await input.admin.from(LONGFORM_APPENDIX_TABLE).upsert({
      report_id: input.reportId,
      user_id: input.userId,
      request_id: input.requestId,
      status: next.status,
      markdown: next.markdown,
      content_sha256: next.contentSha256,
      attempt_count: next.attemptCount,
      last_error_code: next.lastErrorCode,
      generated_at: next.status === "ready" ? new Date().toISOString() : null,
      updated_at: new Date().toISOString(),
    }, { onConflict: "report_id" });
    if (result.error) {
      throw new LongformGenerateError("calculation_unavailable", true, "appendix_persist_failed");
    }
  } catch (error) {
    if (error instanceof LongformGenerateError) throw error;
    throw new LongformGenerateError("calculation_unavailable", true, "appendix_persist_failed");
  }
}

async function fetchLongformMarkdown(input: Readonly<{
  payload: Record<string, unknown>;
  apiBase: string;
  fetchImpl: typeof fetch;
  signal?: AbortSignal;
}>): Promise<string> {
  const timeout = AbortSignal.timeout(ENGINE_TIMEOUT_MS);
  const signal = input.signal
    ? AbortSignal.any([input.signal, timeout])
    : timeout;
  const started = Date.now();
  let httpStatus: number | null = null;
  try {
    const upstream = await input.fetchImpl(`${input.apiBase.replace(/\/$/, "")}/api/professional_report_reference`, {
      method: "POST",
      headers: { "Content-Type": "application/json", Accept: "application/json" },
      body: JSON.stringify(input.payload),
      cache: "no-store",
      signal,
    });
    httpStatus = upstream.status;
    if (!upstream.ok) {
      throw new LongformGenerateError(
        "calculation_unavailable",
        true,
        upstream.status === 429 ? "upstream_busy" : "upstream_unavailable",
      );
    }
    const result = await upstream.json().catch(() => null) as { format?: unknown; markdown?: unknown } | null;
    if (result?.format !== "markdown" || typeof result.markdown !== "string" || !result.markdown.trim()) {
      throw new LongformGenerateError("calculation_unavailable", true, "empty_markdown");
    }
    return result.markdown;
  } catch (error) {
    throw error;
  } finally {
    const durationMs = Date.now() - started;
    if (httpStatus !== null) {
      console.info(`[personal-report] engine http_status=${httpStatus} duration_ms=${durationMs}`);
    } else {
      console.info(`[personal-report] engine http_status=error duration_ms=${durationMs}`);
    }
  }
}

export async function generatePersonalReportLongform(
  deps: LongformGenerateDeps,
): Promise<GeneratePersonalReportResult> {
  const profile = record(deps.profile);
  if (!profile) {
    throw new LongformGenerateError("report_schema_invalid", false);
  }
  const today = utcToday(deps.now?.() ?? new Date());
  const range = deps.candidateRange
    ? { start_time: deps.candidateRange.startTime, end_time: deps.candidateRange.endTime }
    : null;
  const payload = buildLongformBirthPayload(deps.profile, {
    today,
    targetYear: Number(today.slice(0, 4)),
    candidateRange: range,
    birthTimeAccuracy: range && range.start_time !== range.end_time ? "provisional" : "confirmed",
  });
  if (!payload) {
    throw new LongformGenerateError("birth_time_not_usable", false);
  }

  const current = await readOwnedLongformAppendix(deps.admin, deps.report.id, deps.report.userId);
  let markdown = current?.status === "ready" && current.markdown ? current.markdown : null;
  if (!markdown) {
    try {
      markdown = await fetchLongformMarkdown({
        payload,
        apiBase: deps.apiBase ?? process.env.JYOTISH_API_BASE ?? DEFAULT_API_BASE,
        fetchImpl: deps.fetchImpl ?? fetch,
        signal: deps.signal,
      });
    } catch (error) {
      if (deps.signal?.aborted) throw error;
      await persistLongformAppendix({
        admin: deps.admin,
        reportId: deps.report.id,
        userId: deps.report.userId,
        requestId: deps.report.requestId,
        current,
        errorCode: error instanceof LongformGenerateError ? error.message.slice(0, 80) : "generation_failed",
      }).catch(() => undefined);
      if (error instanceof LongformGenerateError) throw error;
      throw new LongformGenerateError("calculation_unavailable", true);
    }
    await persistLongformAppendix({
      admin: deps.admin,
      reportId: deps.report.id,
      userId: deps.report.userId,
      requestId: deps.report.requestId,
      current,
      successMarkdown: markdown,
    });
  }

  try {
    const document = buildLongformCoverDocument({
      report: deps.report,
      subject: {
        displayName: deps.displayName,
        birthTimeStatus: deps.birthTimeStatus,
        birthPlaceLabel: text(profile.birth_place_label) ?? "未知出生地",
      },
      markdown,
      generatedAt: (deps.now?.() ?? new Date()).toISOString(),
    });
    return {
      status: "ready",
      document,
      evidenceHash: document.provenance.evidenceHash,
    };
  } catch {
    throw new LongformGenerateError("report_schema_invalid", false, "final_parse_rejected");
  }
}