require ('dotenv').config();
const express = require('express');
const {getEnv, PORTS, EPISODIC, logger} = require('@nexusai/shared');
const { getDB } = require('./db');
const { createProject, getProjects, getProject, updateProject, deleteProject } = require('./db/projects');
const { createSummary, getSummary, getSummariesBySession, getSummariesByProject, updateSummary, deleteSummary } = require('./db/summaries');
const { generateAndStoreProjectSummary } = require('./summarization/project');
const graph = require('./graph');

const episodic = require('./episodic');
const semantic = require('./semantic');
const entities = require('./entities');

const app = express();
app.use(express.json({ limit: '2mb' }));

const  PORT = getEnv('PORT', PORTS.MEMORY);

//initialize database on startup
const db = getDB();

semantic.initCollections()
    .then(() => logger.info(`QDrant collections ready`))
    .catch(err => logger.error(`QDrant initialization error:`, err.message));

// Health check endpoint
app.get('/health', (req, res) => {
    res.json({ service: 'Memory Service', status: 'healthy' });
});

/************************************ */
/********** Session Routes ********** */
/************************************ */

// Creates a new session with an external ID and optional metadata
app.get('/sessions', (req, res) => {
  const { 
    limit = EPISODIC.DEFAULT_PAGE_SIZE, 
    offset = EPISODIC.DEFAULT_OFFSET, 
    projectId 
  } = req.query;
  
  const parsedProjectId = projectId && projectId !== 'null' ? Number(projectId) : null;
  
  const sessions = episodic.getSessions(Number(limit), Number(offset), parsedProjectId);
  res.json(sessions);
});

app.post('/sessions', (req, res) => {
  const { externalId, metadata } = req.body;
  if (!externalId) {
    return res.status(400).json({ error: 'externalId is required' });
  }
  try {
    const session = episodic.createSession(externalId, metadata);
    res.status(201).json(session);
  } catch (err) {
    res.status(409).json({ error: 'Session already exists', detail: err.message });
  }
});

// Retrieves a session by its external ID
app.get('/sessions/by-external/:externalId', (req, res) => {
  const session = episodic.getSessionByExternalId(req.params.externalId);
  if (!session) return res.status(404).json({ error: 'Session not found' });
  res.json(session);
});



// Retrieves a session by its internal ID
app.get('/sessions/:id', (req, res) => {
  const session = episodic.getSession(req.params.id);
  if (!session) return res.status(404).json({ error: 'Session not found' });
  res.json(session);
});

app.patch('/sessions/by-external/:externalId', (req, res) => {
  const { name, projectId } = req.body;
  try {
    const session = episodic.updateSessionByExternalId(req.params.externalId, {name, projectId });
    res.json(session);
  } catch (err) {
    res.status(500).json({ error: 'Failed to update session', detail: err.message });
  }
});

// Deletes a session and all associated episodes
app.delete('/sessions/by-external/:externalId', (req, res) => {
  episodic.deleteSessionByExternalId(req.params.externalId);
  res.status(204).send();
});


/************************************* */
/********** Episodic Routes ********** */
/************************************* */

app.post('/episodes', async (req, res) => {
  const { sessionId, userMessage, aiResponse, tokenCount, projectId } = req.body;
  if (!sessionId || !userMessage || !aiResponse) {
    return res.status(400).json({ error: 'sessionId, userMessage and aiResponse are required' });
  }
  const episode = await episodic.createEpisode(sessionId, userMessage, aiResponse, tokenCount, projectId);

  res.status(201).json(episode);
});

app.get('/episodes', (req, res) => {
  const { limit = 50, offset = 0, sessionId, q } = req.query;

  if (q) {
    const results = episodic.searchEpisodes(q, Number(limit));
    return res.json({ episodes: results, total: results.length });
  }

  const db = getDB();
  let episodes;

  if (sessionId) {
    episodes = episodic.getEpisodesBySession(Number(sessionId), Number(limit), Number(offset));
  } else {
    episodes = db.prepare(
      `SELECT * FROM episodes ORDER BY created_at DESC LIMIT ? OFFSET ?`
    ).all(Number(limit), Number(offset)).map(row => require('@nexusai/shared').parseRow(row));
  }

  const total = db.prepare(`SELECT COUNT(*) as count FROM episodes`).get().count;
  res.json({ episodes, total });
});

// Search MUST come before /:id — otherwise 'search' gets captured as an id
app.get('/episodes/search', (req, res) => {
  const { q, limit = EPISODIC.DEFAULT_PAGE_SIZE, sessionIds } = req.query;
  if (!q) return res.status(400).json({ error: 'q (query) parameter is required' });
  const parsedSessionIds = sessionIds
    ? sessionIds.split(',').map(Number).filter(Boolean)
    : null;
  res.json(episodic.searchEpisodes(q, Number(limit), parsedSessionIds));
});

app.get('/episodes/:id', (req, res) => {
  const episode = episodic.getEpisode(req.params.id);
  if (!episode) return res.status(404).json({ error: 'Episode not found' });
  res.json(episode);
});

// Get paginated episodes for a session
app.get('/sessions/:id/episodes', (req, res) => {
  const { limit = EPISODIC.DEFAULT_PAGE_SIZE, offset = EPISODIC.DEFAULT_OFFSET } = req.query;
  const episodes = episodic.getEpisodesBySession(
    req.params.id,
    Number(limit),
    Number(offset)
  );
  res.json(episodes);
});

app.delete('/episodes/:id', (req, res) => {
  const id = Number(req.params.id);
  episodic.deleteEpisode(id);

  semantic.deleteEpisode(id)  // fire-and-forget
    .catch(err => logger.error(`[Memory] Qdrant delete failed for episode ${id}:`, err.message));

  res.status(204).send();
});

/*********************************** */
/********** Entity Routes ********** */
/*********************************** */
//Upsert an entity, creates or updates if already exists
app.post('/entities', (req, res) => {
  const {name, type, notes, metadata} = req.body;
  if (!name || !type) {
    return res.status(400).json({ error: 'name and type are required' });
  }
  const entity = entities.upsertEntity(name, type, notes, metadata);
  res.status(201).json(entity);
});

// Get all entities of a given type
app.get('/entities/by-type/:type', (req, res) => {
  res.json(entities.getEntitiesByType(req.params.type));
});

// Get an entity by ID
app.get('/entities/:id', (req, res) => {
  const entity = entities.getEntity(req.params.id);
  if (!entity) return res.status(404).json({ error: 'Entity not found' });
  res.json(entity);
});



// Delete an entity by ID
app.delete('/entities/:id', (req, res) => {
  entities.deleteEntity(req.params.id);
  res.status(204).send();
});

/***************************************** */
/********** Relationship Routes ********** */
/***************************************** */

// Upsert a relationship between two entities
app.post('/relationships', (req, res) => {
  const { fromId, toId, label, notes, metadata } = req.body;
  if (!fromId || !toId || !label) {
    return res.status(400).json({ error: 'fromId, toId and label are required' });
  }
  const relationship = entities.upsertRelationship(fromId, toId, label, notes, metadata);
  res.status(201).json(relationship);
});

// Get all relationships for a given entity ID
app.get('/entities/:id/relationships', (req, res) => {
  res.json(entities.getOutboundRelationships(req.params.id));
});

// Delete a specific relationship
app.delete('/relationships', (req, res) => {
  const {fromId, toId, label} = req.body;
  if (!fromId || !toId || !label) {
    return res.status(400).json({ error: 'fromId, toId and label are required' });
  }
  entities.deleteRelationship(fromId, toId, label);
  res.status(204).send();
})

/********************************* */
/********** Graph Routes ********** */
/********************************* */

// Single-entity neighborhood — depth defaults to ENTITIES.GRAPH_HOP_DEPTH
app.get('/graph/neighborhood/:entityId', (req, res) => {
    const entity = entities.getEntity(req.params.entityId);
    if (!entity) return res.status(404).json({ error: 'Entity not found' });

    const depth = req.query.depth ? Math.min(Number(req.query.depth), 3) : undefined;
    const neighborhood = graph.getNeighborhood(Number(req.params.entityId), depth);
    res.json({ entity, neighborhood });
});

// Bulk 1-hop neighborhood — body: { entityIds: [...] }
app.post('/graph/neighbors', (req, res) => {
    const { entityIds } = req.body;
    if (!Array.isArray(entityIds) || entityIds.length === 0) {
        return res.status(400).json({ error: 'entityIds array is required' });
    }
    res.json(graph.getEntityNeighbors(entityIds.map(Number)));
});

app.post('/episodes/by-entities', (req, res) => {
    const { entityIds } = req.body;
    if (!Array.isArray(entityIds) || entityIds.length === 0) {
        return res.status(400).json({ error: 'entityIds array is required' });
    }
    res.json({ episodeIds: graph.getEpisodeIdsByEntities(entityIds.map(Number)) });
});

/*********************************** */
/********** Project Routes ********** */
/*********************************** */

app.post('/projects', (req, res) => {
  const { name, description, colour, icon } = req.body;
  if (!name?.trim()) return res.status(400).json({ error: 'name is required' });
  try {
    res.status(201).json(createProject({ name: name.trim(), description, colour, icon }));
  } catch (err) {
    res.status(500).json({ error: 'Failed to create project', detail: err.message });
  }
});

app.get('/projects', (req, res) => {
  res.json(getProjects());
});

// Generate (or regenerate) a project overview summary on demand
app.post('/projects/:id/summarize', async (req, res) => {
    const project = getProject(Number(req.params.id));
    if (!project) return res.status(404).json({ error: 'Project not found' });

    try {
        const summary = await generateAndStoreProjectSummary(Number(req.params.id));
        res.status(201).json(summary);
    } catch (err) {
        if (err.message.includes('No session summaries or episodes')) {
            return res.status(422).json({ error: err.message });
        }
        res.status(500).json({ error: 'Failed to generate project summary', detail: err.message });
    }
});

// Get the current project overview summary
app.get('/projects/:id/overview', async (req, res) => {
    const { getProjectOverviewSummary } = require('./db/summaries');
    const summary = getProjectOverviewSummary(Number(req.params.id));
    // 200 with null is fine — frontend can handle "no overview yet" gracefully
    res.json(summary ?? null);
});

// Get summaries for a project
app.get('/projects/:id/summaries', (req, res) => {
    res.json(getSummariesByProject(req.params.id));
});

app.get('/projects/:id', (req, res) => {
  const project = getProject(req.params.id);
  if (!project) return res.status(404).json({ error: 'Not found' });
  res.json(project);
});

app.patch('/projects/:id', (req, res) => {
  const project = getProject(req.params.id);
  if (!project) return res.status(404).json({ error: 'Not found' });
  res.json(updateProject(req.params.id, req.body));
});

app.delete('/projects/:id', (req, res) => {
  const project = getProject(req.params.id);
  if (!project) return res.status(404).json({ error: 'Not found' });
  deleteProject(req.params.id);
  res.status(204).send();
});






/*********************************** */
/********** Summary Routes ********** */
/*********************************** */

// Create a summary (called by orchestration, fire-and-forget style)
app.post('/summaries', (req, res) => {
    const { sessionId, projectId, content, tokenCount, episodeRange, metadata } = req.body;
    if (!content) return res.status(400).json({ error: 'content is required' });
    if (!sessionId && !projectId) return res.status(400).json({ error: 'sessionId or projectId is required' });

    try {
        const summary = createSummary({ sessionId, projectId, content, tokenCount, episodeRange, metadata });
        res.status(201).json(summary);
    } catch (err) {
        res.status(500).json({ error: 'Failed to create summary', detail: err.message });
    }
});

// Get summaries for a session
app.get('/sessions/:id/summaries', (req, res) => {
    res.json(getSummariesBySession(req.params.id));
});

// Update a summary (for cumulative updates)
app.patch('/summaries/:id', (req, res) => {
    const summary = getSummary(req.params.id);
    if (!summary) return res.status(404).json({ error: 'Not found' });
    res.json(updateSummary(req.params.id, req.body));
});

// Delete a summary
app.delete('/summaries/:id', (req, res) => {
    deleteSummary(req.params.id);
    res.status(204).send();
});



/********************************** */
/********** Start Server ********** */
/********************************** */
app.listen(PORT, () => {
    logger.info(`Memory Service is running on port ${PORT}`);
});