import { homedir } from 'os';
import { dirname, join, resolve } from 'path';
import { readFileSync, existsSync, mkdirSync, writeFileSync, readdirSync } from 'fs';
import { deriveBankId, prepareRetentionTranscript } from './index.js';
import type { PluginConfig, PluginHookAgentContext } from './types.js';

export interface BackfillCliOptions {
  openclawRoot: string;
  includeArchive: boolean;
  selectedAgents?: Set<string>;
  limit?: number;
  bankStrategy: 'mirror-config' | 'agent' | 'fixed';
  fixedBank?: string;
}

export interface SessionMessage {
  role: 'user' | 'assistant' | 'system' | 'tool';
  content: string | Array<{ type?: string; text?: string }>;
}

export interface ParsedSessionFile {
  filePath: string;
  agentId: string;
  sessionId: string;
  sessionKey?: string;
  startedAt?: string;
  messages: SessionMessage[];
}

export interface BackfillPlanEntry {
  filePath: string;
  agentId: string;
  sessionId: string;
  startedAt?: string;
  bankId: string;
  documentId: string;
  transcript: string;
  messageCount: number;
}

export interface BackfillCheckpointEntry {
  status: 'enqueued' | 'completed' | 'failed';
  bankId: string;
  filePath: string;
  sessionId: string;
  updatedAt: string;
  error?: string;
}

export interface BackfillCheckpoint {
  version: 1;
  entries: Record<string, BackfillCheckpointEntry>;
}

interface RawBackfillCheckpointEntry extends Omit<BackfillCheckpointEntry, 'status'> {
  status: BackfillCheckpointEntry['status'] | 'queued';
}

interface RawBackfillCheckpoint {
  version: 1;
  entries: Record<string, RawBackfillCheckpointEntry>;
}

interface SessionDirectory {
  agentId: string;
  path: string;
}

const DEFAULT_PLUGIN_CONFIG: PluginConfig = {
  dynamicBankId: true,
  retainRoles: ['user', 'assistant'],
};

export function defaultOpenClawRoot(): string {
  return resolve(join(homedir(), '.openclaw'));
}

export function defaultCheckpointPath(openclawRoot: string): string {
  return join(openclawRoot, 'data', 'hindsight-backfill-checkpoint.json');
}

export function loadPluginConfigFromOpenClawRoot(openclawRoot: string): PluginConfig {
  const configPath = join(openclawRoot, 'openclaw.json');
  const raw = JSON.parse(readFileSync(configPath, 'utf8')) as {
    plugins?: { entries?: Record<string, { config?: PluginConfig }> };
  };
  return {
    ...DEFAULT_PLUGIN_CONFIG,
    ...(raw.plugins?.entries?.['hindsight-openclaw']?.config || {}),
  };
}

function extractTextContent(content: unknown): string {
  if (typeof content === 'string') {
    return content;
  }
  if (Array.isArray(content)) {
    return content
      .filter((block): block is { type?: string; text?: string } => !!block && typeof block === 'object')
      .filter((block) => block.type === 'text' && typeof block.text === 'string')
      .map((block) => block.text || '')
      .join('\n');
  }
  return '';
}

function readJsonLines(filePath: string): unknown[] {
  const content = readFileSync(filePath, 'utf8');
  return content
    .split('\n')
    .map((line) => line.trim())
    .filter(Boolean)
    .map((line) => JSON.parse(line));
}

export function parseSessionFile(filePath: string, agentId: string): ParsedSessionFile {
  const records = readJsonLines(filePath) as Array<Record<string, any>>;
  let sessionId = filePath.split('/').pop()?.replace(/\.jsonl$/, '') || 'session';
  let sessionKey: string | undefined;
  let startedAt: string | undefined;
  const messages: SessionMessage[] = [];

  for (const record of records) {
    if (record.type === 'session') {
      sessionId = typeof record.id === 'string' ? record.id : sessionId;
      startedAt = typeof record.timestamp === 'string' ? record.timestamp : startedAt;
      sessionKey = typeof record.sessionKey === 'string' ? record.sessionKey : sessionKey;
      continue;
    }
    if (record.type !== 'message' || !record.message || typeof record.message !== 'object') {
      continue;
    }
    const message = record.message as Record<string, unknown>;
    const role = message.role;
    if (role !== 'user' && role !== 'assistant' && role !== 'system' && role !== 'tool') {
      continue;
    }
    const text = extractTextContent(message.content);
    if (!text.trim()) {
      continue;
    }
    messages.push({
      role,
      content: typeof message.content === 'string' ? message.content : [{ type: 'text', text }],
    });
    if (!sessionKey && typeof record.sessionKey === 'string') {
      sessionKey = record.sessionKey;
    }
  }

  return {
    filePath,
    agentId,
    sessionId,
    sessionKey,
    startedAt,
    messages,
  };
}

function sessionDirectories(openclawRoot: string, includeArchive: boolean): SessionDirectory[] {
  const agentsRoot = join(openclawRoot, 'agents');
  if (!existsSync(agentsRoot)) {
    return [];
  }
  const result: SessionDirectory[] = [];
  for (const entry of readdirSync(agentsRoot, { withFileTypes: true })) {
    if (!entry.isDirectory()) continue;
    const agentId = entry.name;
    const sessionsDir = join(agentsRoot, agentId, 'sessions');
    if (existsSync(sessionsDir)) {
      result.push({ agentId, path: sessionsDir });
    }
    if (includeArchive) {
      const archiveDir = join(agentsRoot, agentId, 'sessions-archive-from-migration_backup');
      if (existsSync(archiveDir)) {
        result.push({ agentId, path: archiveDir });
      }
    }
  }
  return result.sort((a, b) => a.agentId.localeCompare(b.agentId) || a.path.localeCompare(b.path));
}

export function discoverSessionFiles(openclawRoot: string, includeArchive: boolean): Array<{ agentId: string; filePath: string }> {
  const sessions: Array<{ agentId: string; filePath: string }> = [];
  for (const dir of sessionDirectories(openclawRoot, includeArchive)) {
    for (const entry of readdirSync(dir.path, { withFileTypes: true })) {
      if (!entry.isFile() || !entry.name.endsWith('.jsonl')) continue;
      sessions.push({
        agentId: dir.agentId,
        filePath: join(dir.path, entry.name),
      });
    }
  }
  return sessions.sort((a, b) => a.agentId.localeCompare(b.agentId) || a.filePath.localeCompare(b.filePath));
}

function backfillContextForSession(session: ParsedSessionFile): PluginHookAgentContext {
  return {
    agentId: session.agentId,
    sessionKey: session.sessionKey,
  };
}

function deriveTargetBank(
  session: ParsedSessionFile,
  pluginConfig: PluginConfig,
  bankStrategy: BackfillCliOptions['bankStrategy'],
  fixedBank?: string,
): string {
  if (bankStrategy === 'agent') {
    return session.agentId;
  }
  if (bankStrategy === 'fixed') {
    if (!fixedBank) {
      throw new Error('fixed bank strategy requires --fixed-bank');
    }
    return fixedBank;
  }
  return deriveBankId(backfillContextForSession(session), pluginConfig);
}

export function stableDocumentId(session: ParsedSessionFile, bankId: string): string {
  return `backfill::${bankId}::${session.agentId}::${session.sessionId}`;
}

export function buildBackfillPlan(
  pluginConfig: PluginConfig,
  opts: BackfillCliOptions,
): { entries: BackfillPlanEntry[]; discoveredSessions: number; skippedEmpty: number } {
  const entries: BackfillPlanEntry[] = [];
  let discoveredSessions = 0;
  let skippedEmpty = 0;

  for (const candidate of discoverSessionFiles(opts.openclawRoot, opts.includeArchive)) {
    if (opts.selectedAgents && !opts.selectedAgents.has(candidate.agentId)) {
      continue;
    }
    discoveredSessions += 1;
    const parsed = parseSessionFile(candidate.filePath, candidate.agentId);
    const retention = prepareRetentionTranscript(parsed.messages, pluginConfig, true);
    if (!retention) {
      skippedEmpty += 1;
      continue;
    }
    const bankId = deriveTargetBank(parsed, pluginConfig, opts.bankStrategy, opts.fixedBank);
    entries.push({
      filePath: parsed.filePath,
      agentId: parsed.agentId,
      sessionId: parsed.sessionId,
      startedAt: parsed.startedAt,
      bankId,
      documentId: stableDocumentId(parsed, bankId),
      transcript: retention.transcript,
      messageCount: retention.messageCount,
    });
    if (opts.limit && entries.length >= opts.limit) {
      break;
    }
  }

  return { entries, discoveredSessions, skippedEmpty };
}

export function loadCheckpoint(checkpointPath: string): BackfillCheckpoint {
  if (!existsSync(checkpointPath)) {
    return { version: 1, entries: {} };
  }
  const raw = JSON.parse(readFileSync(checkpointPath, 'utf8')) as RawBackfillCheckpoint;
  if (raw.version !== 1 || !raw.entries || typeof raw.entries !== 'object') {
    return { version: 1, entries: {} };
  }
  return {
    version: 1,
    entries: Object.fromEntries(
      Object.entries(raw.entries).map(([key, entry]) => [
        key,
        {
          ...entry,
          status: entry.status === 'queued' ? 'enqueued' : entry.status,
        },
      ]),
    ) as Record<string, BackfillCheckpointEntry>,
  };
}

export function saveCheckpoint(checkpointPath: string, checkpoint: BackfillCheckpoint): void {
  mkdirSync(dirname(checkpointPath), { recursive: true });
  writeFileSync(checkpointPath, JSON.stringify(checkpoint, null, 2) + '\n', 'utf8');
}

export function checkpointKey(entry: Pick<BackfillPlanEntry, 'bankId' | 'documentId'>): string {
  return `${entry.bankId}::${entry.documentId}`;
}