/**
 * 评估向导草稿持久化（服务端，跨设备）。
 * - source_assessment_id 为空：全新建评估的草稿
 * - source_assessment_id 非空：编辑某既有评估时的草稿
 * form 存完整向导快照（任意 JSON）。
 */
import type pg from 'pg';

export interface DraftRecord {
  id: string;
  assessorId: string | null;
  sourceAssessmentId: string | null;
  projectName: string | null;
  form: unknown;
  updatedAt: string;
}

/** 列表项（不含 form 大字段，仅元信息）。 */
export interface DraftSummary {
  id: string;
  assessorId: string | null;
  sourceAssessmentId: string | null;
  projectName: string | null;
  updatedAt: string;
}

function isoOf(v: unknown): string {
  return v instanceof Date ? v.toISOString() : String(v);
}

/** JSONB 不能存 \u0000（空字符），而指标复合键用其作分隔符。存储时编码为私有区字符，读取时还原。 */
const NUL = '\u0000';
const NUL_SENTINEL = '\uE000';
function deepReplace(value: unknown, from: string, to: string): unknown {
  if (typeof value === 'string') return value.split(from).join(to);
  if (Array.isArray(value)) return value.map((v) => deepReplace(v, from, to));
  if (value !== null && typeof value === 'object') {
    const out: Record<string, unknown> = {};
    for (const [k, v] of Object.entries(value as Record<string, unknown>)) {
      out[k.split(from).join(to)] = deepReplace(v, from, to);
    }
    return out;
  }
  return value;
}
/** 存库前编码（去除 \u0000）。 */
function encodeForm(form: unknown): unknown {
  return deepReplace(form ?? null, NUL, NUL_SENTINEL);
}
/** 读出后还原。 */
function decodeForm(form: unknown): unknown {
  return deepReplace(form ?? null, NUL_SENTINEL, NUL);
}

/** 列出草稿（可按 assessorId 过滤），不返回 form 大字段。 */
export async function listDrafts(pool: pg.Pool, assessorId?: string): Promise<DraftSummary[]> {
  const where = assessorId ? 'WHERE assessor_id = $1' : '';
  const params = assessorId ? [assessorId] : [];
  const res = await pool.query(
    `SELECT id, assessor_id, source_assessment_id, project_name, updated_at
     FROM wizard_drafts ${where} ORDER BY updated_at DESC`,
    params,
  );
  return (res.rows as Array<Record<string, unknown>>).map((r) => ({
    id: String(r.id),
    assessorId: r.assessor_id != null ? String(r.assessor_id) : null,
    sourceAssessmentId: r.source_assessment_id != null ? String(r.source_assessment_id) : null,
    projectName: r.project_name != null ? String(r.project_name) : null,
    updatedAt: isoOf(r.updated_at),
  }));
}

/** 取单个草稿（含 form）。 */
export async function getDraft(pool: pg.Pool, id: string): Promise<DraftRecord | null> {
  const res = await pool.query(
    `SELECT id, assessor_id, source_assessment_id, project_name, form, updated_at
     FROM wizard_drafts WHERE id = $1`,
    [id],
  );
  const r = (res.rows as Array<Record<string, unknown>>)[0];
  if (!r) return null;
  return {
    id: String(r.id),
    assessorId: r.assessor_id != null ? String(r.assessor_id) : null,
    sourceAssessmentId: r.source_assessment_id != null ? String(r.source_assessment_id) : null,
    projectName: r.project_name != null ? String(r.project_name) : null,
    form: decodeForm(r.form),
    updatedAt: isoOf(r.updated_at),
  };
}

export interface UpsertDraftInput {
  id: string;
  assessorId?: string | null;
  sourceAssessmentId?: string | null;
  projectName?: string | null;
  form: unknown;
}

/** 新增或更新草稿（按 id）。 */
export async function upsertDraft(pool: pg.Pool, input: UpsertDraftInput): Promise<DraftRecord> {
  const res = await pool.query(
    `INSERT INTO wizard_drafts(id, assessor_id, source_assessment_id, project_name, form, updated_at)
     VALUES($1,$2,$3,$4,$5,now())
     ON CONFLICT(id) DO UPDATE SET
       assessor_id = EXCLUDED.assessor_id,
       source_assessment_id = EXCLUDED.source_assessment_id,
       project_name = EXCLUDED.project_name,
       form = EXCLUDED.form,
       updated_at = now()
     RETURNING id, assessor_id, source_assessment_id, project_name, form, updated_at`,
    [
      input.id,
      input.assessorId ?? null,
      input.sourceAssessmentId ?? null,
      input.projectName ?? null,
      JSON.stringify(encodeForm(input.form)),
    ],
  );
  const r = (res.rows as Array<Record<string, unknown>>)[0]!;
  return {
    id: String(r.id),
    assessorId: r.assessor_id != null ? String(r.assessor_id) : null,
    sourceAssessmentId: r.source_assessment_id != null ? String(r.source_assessment_id) : null,
    projectName: r.project_name != null ? String(r.project_name) : null,
    form: decodeForm(r.form),
    updatedAt: isoOf(r.updated_at),
  };
}

/** 删除草稿。 */
export async function deleteDraft(pool: pg.Pool, id: string): Promise<void> {
  await pool.query('DELETE FROM wizard_drafts WHERE id = $1', [id]);
}