import { Router } from 'express';
import { z } from 'zod';
import * as repo from '../../db/repos/pages.js';
import * as links from '../../db/repos/links.js';
import { pool } from '../../db/pool.js';
import { validate } from '../validate.js';
import { NotFoundError, ValidationError, asyncWrap } from '../errors.js';

const createSchema = z.object({
  slug: z.string().min(1).max(128).regex(/^[a-z0-9-]+$/),
  title: z.string().min(1).max(500),
  body_md: z.string().optional(),
  parent_id: z.string().uuid().nullable().optional()
});

const patchSchema = z.object({
  slug: z.string().min(1).max(128).regex(/^[a-z0-9-]+$/).optional(),
  title: z.string().min(1).max(500).optional(),
  body_md: z.string().optional(),
  body_html: z.string().nullable().optional(),
  parent_id: z.string().uuid().nullable().optional()
});

const idParams = z.object({ id: z.string().uuid() });
const spaceParams = z.object({ space_id: z.string().uuid() });
const spaceSlugParams = z.object({ space_id: z.string().uuid(), slug: z.string().min(1) });

export const router = Router();
export const spacesScopedRouter = Router({ mergeParams: true });

spacesScopedRouter.get('/',
  validate({ params: spaceParams }),
  asyncWrap(async (req, res) => { res.json(await repo.listBySpace(req.params.space_id)); })
);

spacesScopedRouter.post('/',
  validate({ params: spaceParams, body: createSchema }),
  asyncWrap(async (req, res) => {
    try {
      const row = await repo.create({ ...req.body, space_id: req.params.space_id }, req.actor);
      res.status(201).json(row);
    } catch (e) {
      if (e.code === '23503') throw new ValidationError('invalid space or parent', {
        space_id: req.params.space_id, parent_id: req.body.parent_id
      });
      if (e.code === '23505') throw new ValidationError('slug already used in space', { slug: req.body.slug });
      throw e;
    }
  })
);

spacesScopedRouter.get('/by-slug/:slug',
  validate({ params: spaceSlugParams }),
  asyncWrap(async (req, res) => {
    const row = await repo.getBySlug(req.params.space_id, req.params.slug);
    if (!row) throw new NotFoundError('page not found');
    res.json(row);
  })
);

router.get('/:id',
  validate({ params: idParams }),
  asyncWrap(async (req, res) => {
    const row = await repo.getById(req.params.id);
    if (!row) throw new NotFoundError('page not found');
    res.json(row);
  })
);

router.patch('/:id',
  validate({ params: idParams, body: patchSchema }),
  asyncWrap(async (req, res) => {
    const existing = await repo.getById(req.params.id);
    if (!existing) throw new NotFoundError('page not found');
    const row = await repo.update(req.params.id, req.body, req.actor);
    res.json(row);
  })
);

router.delete('/:id',
  validate({ params: idParams }),
  asyncWrap(async (req, res) => {
    const existing = await repo.getById(req.params.id);
    if (!existing) throw new NotFoundError('page not found');
    await repo.del(req.params.id, req.actor);
    res.status(204).end();
  })
);

router.get('/:id/revisions',
  validate({ params: idParams }),
  asyncWrap(async (req, res) => {
    const existing = await repo.getById(req.params.id);
    if (!existing) throw new NotFoundError('page not found');
    res.json(await repo.listRevisions(req.params.id));
  })
);

const TITLE_BY_TYPE = {
  space: 'name', project: 'name', task: 'title', page: 'title',
  ref: 'title', resource: 'name', source_doc: 'name', conversation: 'title'
};

router.get('/:id/backlinks',
  validate({ params: idParams }),
  asyncWrap(async (req, res) => {
    const existing = await repo.getById(req.params.id);
    if (!existing) throw new NotFoundError('page not found');
    const rows = await links.listTo('page', req.params.id);
    const enriched = await Promise.all(rows.map(async link => {
      const col = TITLE_BY_TYPE[link.from_type];
      if (!col) return { ...link, source_title: null };
      const table = link.from_type + 's';
      try {
        const { rows: [src] } = await pool.query(
          `SELECT ${col} AS title FROM ${table} WHERE id=$1`, [link.from_id]
        );
        return { ...link, source_title: src?.title || null };
      } catch { return { ...link, source_title: null }; }
    }));
    res.json(enriched);
  })
);