const express = require('express');
const db = require('../db');

const router = express.Router({ mergeParams: true });

const STATUSES = ['active', 'resolved', 'suspended', 'complicated'];

const OPTIONAL_TEXT_FIELDS = [
  'notes',
  'related_npcs',
  'related_location',
  'origin',
  'stakes',
  'last_development',
  'next_beat',
  'suspected_resolution',
];

const getCampaignByIdStmt = db.prepare('SELECT id FROM campaigns WHERE id = ?');
const listThreadsStmt = db.prepare('SELECT * FROM threads WHERE campaign_id = ? ORDER BY created_at DESC');
const getThreadStmt = db.prepare('SELECT * FROM threads WHERE id = ? AND campaign_id = ?');

const insertThreadStmt = db.prepare(`
  INSERT INTO threads (
    campaign_id, title, status, notes, related_npcs, related_location,
    origin, stakes, last_development, next_beat, suspected_resolution
  ) VALUES (
    @campaign_id, @title, @status, @notes, @related_npcs, @related_location,
    @origin, @stakes, @last_development, @next_beat, @suspected_resolution
  )
`);

const updateThreadStmt = db.prepare(`
  UPDATE threads SET
    title = @title,
    status = @status,
    notes = @notes,
    related_npcs = @related_npcs,
    related_location = @related_location,
    origin = @origin,
    stakes = @stakes,
    last_development = @last_development,
    next_beat = @next_beat,
    suspected_resolution = @suspected_resolution
  WHERE id = @id AND campaign_id = @campaign_id
`);

const deleteThreadStmt = db.prepare('DELETE FROM threads WHERE id = ? AND campaign_id = ?');

function parsePositiveInt(raw, res, label) {
  const value = Number(raw);
  if (!Number.isInteger(value) || value <= 0) {
    res.status(400).json({ error: `${label} must be a positive integer` });
    return null;
  }
  return value;
}

function loadCampaignId(req, res) {
  const campaignId = parsePositiveInt(req.params.campaignId, res, 'campaign_id');
  if (campaignId === null) return null;

  if (!getCampaignByIdStmt.get(campaignId)) {
    res.status(404).json({ error: 'campaign not found' });
    return null;
  }
  return campaignId;
}

// Shared by create and update — PUT sends the full form, so both treat
// title/status the same way rather than supporting partial patches.
function parseThreadPayload(body, res) {
  const title = typeof body.title === 'string' ? body.title.trim() : '';
  if (!title) {
    res.status(400).json({ error: 'title is required' });
    return null;
  }

  const status = body.status === undefined ? 'active' : body.status;
  if (!STATUSES.includes(status)) {
    res.status(400).json({ error: `status must be one of: ${STATUSES.join(', ')}` });
    return null;
  }

  const payload = { title, status };

  for (const field of OPTIONAL_TEXT_FIELDS) {
    const value = body[field];
    if (value === undefined || value === null) {
      payload[field] = null;
    } else if (typeof value === 'string') {
      payload[field] = value;
    } else {
      res.status(400).json({ error: `${field} must be a string or null` });
      return null;
    }
  }

  return payload;
}

function withErrorHandling(handler) {
  return (req, res) => {
    try {
      handler(req, res);
    } catch (err) {
      console.error(err);
      res.status(500).json({ error: 'unexpected server error' });
    }
  };
}

router.get('/', withErrorHandling((req, res) => {
  const campaignId = loadCampaignId(req, res);
  if (campaignId === null) return;

  res.json({ data: listThreadsStmt.all(campaignId) });
}));

router.get('/:id', withErrorHandling((req, res) => {
  const campaignId = loadCampaignId(req, res);
  if (campaignId === null) return;

  const id = parsePositiveInt(req.params.id, res, 'id');
  if (id === null) return;

  const thread = getThreadStmt.get(id, campaignId);
  if (!thread) {
    return res.status(404).json({ error: 'thread not found' });
  }
  res.json({ data: thread });
}));

router.post('/', withErrorHandling((req, res) => {
  const campaignId = loadCampaignId(req, res);
  if (campaignId === null) return;

  const payload = parseThreadPayload(req.body, res);
  if (payload === null) return;

  const result = insertThreadStmt.run({ ...payload, campaign_id: campaignId });
  res.status(201).json({ data: getThreadStmt.get(result.lastInsertRowid, campaignId) });
}));

router.put('/:id', withErrorHandling((req, res) => {
  const campaignId = loadCampaignId(req, res);
  if (campaignId === null) return;

  const id = parsePositiveInt(req.params.id, res, 'id');
  if (id === null) return;

  if (!getThreadStmt.get(id, campaignId)) {
    return res.status(404).json({ error: 'thread not found' });
  }

  const payload = parseThreadPayload(req.body, res);
  if (payload === null) return;

  updateThreadStmt.run({ ...payload, id, campaign_id: campaignId });
  res.json({ data: getThreadStmt.get(id, campaignId) });
}));

router.delete('/:id', withErrorHandling((req, res) => {
  const campaignId = loadCampaignId(req, res);
  if (campaignId === null) return;

  const id = parsePositiveInt(req.params.id, res, 'id');
  if (id === null) return;

  if (!getThreadStmt.get(id, campaignId)) {
    return res.status(404).json({ error: 'thread not found' });
  }

  deleteThreadStmt.run(id, campaignId);
  res.json({ data: { id } });
}));

module.exports = router;