import type { Config, WebhookEvent, RepoConfig } from './types.js';
import {
  listRecentComments,
  fetchPR,
  fetchIssue,
  hasExistingComment,
  postComment,
  updateComment,
  formatComment,
  createReaction,
  type RecentComment,
} from './github.js';
import { createEngine } from './engine/index.js';
import { getLogger } from './logger.js';
import { recordEvent } from './events.js';
import { readFileSync, writeFileSync, existsSync } from 'fs';

interface ProcessedComment {
  id: number;
  timestamp: number;
}

interface PollingState {
  lastProcessedAt: Record<string, string>;
}

const processedComments: Map<string, ProcessedComment> = new Map();
const MAX_PROCESSED_CACHE = 1000;

let pollingState: PollingState = { lastProcessedAt: {} };

function loadPollingState(stateFile: string): void {
  if (existsSync(stateFile)) {
    try {
      const data = readFileSync(stateFile, 'utf-8');
      const parsed = JSON.parse(data);
      // Validate that parsed data has expected structure
      if (
        parsed &&
        typeof parsed === 'object' &&
        parsed.lastProcessedAt &&
        typeof parsed.lastProcessedAt === 'object'
      ) {
        pollingState = parsed;
      } else {
        getLogger().warn('Invalid polling state format, resetting to empty state');
        pollingState = { lastProcessedAt: {} };
      }
    } catch {
      // Ignore parse errors, use empty state
      pollingState = { lastProcessedAt: {} };
    }
  }
}

function savePollingState(stateFile: string): void {
  try {
    writeFileSync(stateFile, JSON.stringify(pollingState, null, 2));
  } catch (err) {
    getLogger().warn('Failed to save polling state', err);
  }
}

function getRepoKey(owner: string, repo: string): string {
  return `${owner}/${repo}`;
}

function getLastProcessedAt(owner: string, repo: string): Date | undefined {
  const key = getRepoKey(owner, repo);
  const timestamp = pollingState.lastProcessedAt[key];
  return timestamp ? new Date(timestamp) : undefined;
}

function setLastProcessedAt(owner: string, repo: string, date: Date): void {
  const key = getRepoKey(owner, repo);
  pollingState.lastProcessedAt[key] = date.toISOString();
}

function getCacheKey(owner: string, repo: string, commentId: number): string {
  return `${owner}/${repo}#${commentId}`;
}

function isProcessed(owner: string, repo: string, commentId: number): boolean {
  return processedComments.has(getCacheKey(owner, repo, commentId));
}

function markProcessed(owner: string, repo: string, commentId: number): void {
  const key = getCacheKey(owner, repo, commentId);
  processedComments.set(key, { id: commentId, timestamp: Date.now() });

  // Clean up old entries if cache is too large
  if (processedComments.size > MAX_PROCESSED_CACHE) {
    const entries = Array.from(processedComments.entries());
    entries.sort((a, b) => a[1].timestamp - b[1].timestamp);
    const toRemove = entries.slice(0, entries.length - MAX_PROCESSED_CACHE);
    for (const [k] of toRemove) {
      processedComments.delete(k);
    }
  }
}

function containsMention(body: string): boolean {
  return body.includes('@troutbot');
}

async function analyzeAndComment(
  event: WebhookEvent,
  config: Config
): Promise<Record<string, unknown>> {
  const logger = getLogger();
  const engine = createEngine(config.engine);

  // Run analysis
  const analysis = await engine.analyze(event);
  logger.info(
    `Analyzed ${event.owner}/${event.repo}#${event.number}: impact=${analysis.impact}, confidence=${analysis.confidence.toFixed(2)}`
  );

  // Check for existing comment
  const { commentMarker, allowUpdates } = config.response;
  const existing = await hasExistingComment(event.owner, event.repo, event.number, commentMarker);

  if (existing.exists && !allowUpdates) {
    logger.info(`Already commented on ${event.owner}/${event.repo}#${event.number}, skipping`);
    const result = { skipped: true, reason: 'Already commented' };
    recordEvent(event, result, analysis);
    return result;
  }

  const body = formatComment(
    config.response,
    event.type,
    analysis.impact,
    analysis.confidence,
    analysis.reasoning
  );

  if (existing.exists && allowUpdates && existing.commentId) {
    logger.info(`Updating existing comment on ${event.owner}/${event.repo}#${event.number}`);
    await updateComment(event.owner, event.repo, existing.commentId, body);
  } else {
    await postComment(event.owner, event.repo, event.number, body);
  }

  const result = { processed: true, impact: analysis.impact, confidence: analysis.confidence };
  recordEvent(event, result, analysis);
  return result;
}

function isAuthorized(username: string, authorizedUsers?: string[]): boolean {
  if (!authorizedUsers || authorizedUsers.length === 0) {
    return true; // No restrictions
  }
  const normalizedUsername = username.toLowerCase();
  return authorizedUsers.some((u) => u.toLowerCase() === normalizedUsername);
}

function isRepoAuthorized(owner: string, repo: string, pollingRepos?: RepoConfig[]): boolean {
  if (!pollingRepos || pollingRepos.length === 0) {
    return true; // No restrictions, use global repos
  }
  return pollingRepos.some((r) => r.owner === owner && r.repo === repo);
}

async function processComment(
  comment: RecentComment,
  owner: string,
  repo: string,
  config: Config
): Promise<void> {
  const logger = getLogger();

  if (!containsMention(comment.body)) {
    return;
  }

  if (isProcessed(owner, repo, comment.id)) {
    logger.debug(`Comment ${owner}/${repo}#${comment.id} already processed, skipping`);
    return;
  }

  // Check if repo is authorized for polling
  const pollingRepos = config.polling?.repositories;
  if (!isRepoAuthorized(owner, repo, pollingRepos)) {
    logger.info(
      `Unauthorized repo ${owner}/${repo} for polling, ignoring mention from ${comment.author}`
    );
    await createReaction(owner, repo, comment.id, 'thumbs_down');
    markProcessed(owner, repo, comment.id);
    return;
  }

  // Check if user is authorized
  const authorizedUsers = config.polling?.authorizedUsers;
  if (!isAuthorized(comment.author, authorizedUsers)) {
    logger.info(
      `Unauthorized user ${comment.author} attempted on-demand analysis in ${owner}/${repo}#${comment.issueNumber}`
    );
    markProcessed(owner, repo, comment.id);
    return;
  }

  logger.info(`Found @troutbot mention in ${owner}/${repo}#${comment.issueNumber}`);

  try {
    // First, try to fetch as a PR to check if it's a pull request
    const prData = await fetchPR(owner, repo, comment.issueNumber);

    let event: WebhookEvent;

    if (prData) {
      // It's a pull request
      event = {
        action: 'on_demand',
        type: 'pull_request',
        number: comment.issueNumber,
        title: prData.title,
        body: prData.body,
        owner,
        repo,
        author: prData.author,
        labels: prData.labels,
        branch: prData.branch,
        sha: prData.sha,
      };
    } else {
      // It's an issue
      const issueData = await fetchIssue(owner, repo, comment.issueNumber);
      if (!issueData) {
        logger.warn(`Could not fetch issue ${owner}/${repo}#${comment.issueNumber}`);
        return;
      }

      event = {
        action: 'on_demand',
        type: 'issue',
        number: comment.issueNumber,
        title: issueData.title,
        body: issueData.body,
        owner,
        repo,
        author: issueData.author,
        labels: issueData.labels,
      };
    }

    await analyzeAndComment(event, config);
    markProcessed(owner, repo, comment.id);

    logger.info(
      `Successfully processed on-demand analysis for ${owner}/${repo}#${comment.issueNumber}`
    );
  } catch (err) {
    logger.error(`Failed to process mention in ${owner}/${repo}#${comment.issueNumber}`, err);
  }
}

async function pollRepository(
  owner: string,
  repo: string,
  config: Config,
  since: Date,
  stateFile?: string
): Promise<void> {
  const logger = getLogger();

  try {
    const comments = await listRecentComments(owner, repo, since);
    logger.debug(`Fetched ${comments.length} recent comments from ${owner}/${repo}`);

    let latestCommentDate = since;

    for (const comment of comments) {
      await processComment(comment, owner, repo, config);
      const commentDate = new Date(comment.createdAt);
      if (commentDate > latestCommentDate) {
        latestCommentDate = commentDate;
      }
    }

    // Update last processed timestamp
    setLastProcessedAt(owner, repo, latestCommentDate);
    if (stateFile) {
      savePollingState(stateFile);
    }
  } catch (err) {
    logger.error(`Failed to poll ${owner}/${repo}`, err);
  }
}

export async function startPolling(config: Config): Promise<void> {
  const logger = getLogger();
  const pollingConfig = config.polling;

  if (!pollingConfig || !pollingConfig.enabled) {
    logger.info('Polling is disabled');
    return;
  }

  if (config.repositories.length === 0) {
    logger.warn('Polling enabled but no repositories configured');
    return;
  }

  const intervalMs = pollingConfig.intervalMinutes * 60 * 1000;
  const lookbackMs = pollingConfig.lookbackMinutes * 60 * 1000;

  logger.info(`Starting polling for ${config.repositories.length} repositories`);
  logger.info(
    `Poll interval: ${pollingConfig.intervalMinutes} minutes, lookback: ${pollingConfig.lookbackMinutes} minutes`
  );

  // Load persisted state if backfill is enabled
  const stateFile = pollingConfig.backfill
    ? pollingConfig.stateFile || '.troutbot-polling-state.json'
    : undefined;
  if (stateFile) {
    loadPollingState(stateFile);
    logger.info(`Polling state file: ${stateFile}`);
  }

  // Do an initial poll - use persisted timestamp if available, otherwise use lookback
  for (const repo of config.repositories) {
    const lastProcessed = getLastProcessedAt(repo.owner, repo.repo);
    const initialSince = lastProcessed || new Date(Date.now() - lookbackMs);
    if (lastProcessed) {
      logger.info(
        `Resuming polling for ${repo.owner}/${repo.repo} from ${lastProcessed.toISOString()}`
      );
    }
    await pollRepository(repo.owner, repo.repo, config, initialSince, stateFile);
  }

  // Set up recurring polling
  setInterval(async () => {
    const since = new Date(Date.now() - lookbackMs);

    for (const repo of config.repositories) {
      await pollRepository(repo.owner, repo.repo, config, since, stateFile);
    }
  }, intervalMs);
}