import { OPENBRAIN_CONTEXT_ENGINE_ID, OPENBRAIN_PLUGIN_VERSION } from "./constants.js";
import { OpenBrainConfigError } from "./errors.js";
import type {
  AgentMessage,
  AssembleResult,
  BootstrapResult,
  CompactResult,
  ContextEngine,
  ContextEngineInfo,
  IngestBatchResult,
  IngestResult,
  PluginLogger,
  SubagentEndReason,
  SubagentSpawnPreparation,
} from "./openclaw-types.js";
import {
  OpenBrainClient,
  type OpenBrainClientLike,
  type OpenBrainSearchInput,
  type OpenBrainThought,
  type OpenBrainThoughtMetadata,
} from "./openbrain-client.js";

export type OpenBrainContextEngineConfig = {
  baseUrl?: string;
  apiKey?: string;
  recentMessages?: number;
  semanticSearchLimit?: number;
  source?: string;
  subagentRecentMessages?: number;
};

type ResolvedOpenBrainContextEngineConfig = {
  baseUrl: string;
  apiKey: string;
  recentMessages: number;
  semanticSearchLimit: number;
  source: string;
  subagentRecentMessages: number;
};

export type OpenBrainContextEngineDeps = {
  createClient?: (config: ResolvedOpenBrainContextEngineConfig) => OpenBrainClientLike;
  now?: () => number;
  logger?: PluginLogger;
};

type SubagentState = {
  parentSessionKey: string;
  seedThoughtId?: string;
};

function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === "object" && value !== null;
}

function parsePositiveInteger(value: unknown, fallback: number): number {
  if (typeof value !== "number" || !Number.isFinite(value)) {
    return fallback;
  }

  const rounded = Math.floor(value);
  return rounded > 0 ? rounded : fallback;
}

function normalizeRole(role: unknown): string {
  if (typeof role !== "string" || role.length === 0) {
    return "assistant";
  }

  if (role === "user" || role === "assistant" || role === "tool" || role === "system") {
    return role;
  }

  return "assistant";
}

function serializeContent(value: unknown): string {
  if (typeof value === "string") {
    return value;
  }

  if (Array.isArray(value)) {
    return value
      .map((part) => serializeContent(part))
      .filter((part) => part.length > 0)
      .join("\n")
      .trim();
  }

  if (isRecord(value) && typeof value.text === "string") {
    return value.text;
  }

  if (value === undefined || value === null) {
    return "";
  }

  try {
    return JSON.stringify(value);
  } catch {
    return String(value);
  }
}

function estimateTextTokens(text: string): number {
  const normalized = text.trim();
  if (normalized.length === 0) {
    return 1;
  }

  return Math.max(1, Math.ceil(normalized.length / 4) + 4);
}

function thoughtTimestamp(thought: OpenBrainThought, fallbackTimestamp: number): number {
  const createdAt =
    thought.createdAt ??
    (typeof thought.created_at === "string" ? thought.created_at : undefined);

  if (createdAt === undefined) {
    return fallbackTimestamp;
  }

  const parsed = Date.parse(createdAt);
  return Number.isFinite(parsed) ? parsed : fallbackTimestamp;
}

function thoughtFingerprint(thought: OpenBrainThought): string {
  const role = typeof thought.metadata?.role === "string" ? thought.metadata.role : "assistant";
  return `${role}\n${thought.content}`;
}

function truncateLine(value: string, maxLength: number): string {
  if (value.length <= maxLength) {
    return value;
  }

  return `${value.slice(0, maxLength - 3)}...`;
}

export class OpenBrainContextEngine implements ContextEngine {
  readonly info: ContextEngineInfo = {
    id: OPENBRAIN_CONTEXT_ENGINE_ID,
    name: "OpenBrain Context Engine",
    version: OPENBRAIN_PLUGIN_VERSION,
    ownsCompaction: true,
  };

  private readonly rawConfig: unknown;
  private readonly createClientFn:
    | ((config: ResolvedOpenBrainContextEngineConfig) => OpenBrainClientLike)
    | undefined;
  private readonly now: () => number;
  private readonly logger: PluginLogger | undefined;

  private config: ResolvedOpenBrainContextEngineConfig | undefined;
  private client: OpenBrainClientLike | undefined;
  private readonly sessionTurns = new Map<string, number>();
  private readonly subagentState = new Map<string, SubagentState>();
  private disposed = false;

  constructor(rawConfig: unknown, deps?: OpenBrainContextEngineDeps) {
    this.rawConfig = rawConfig;
    this.createClientFn = deps?.createClient;
    this.now = deps?.now ?? (() => Date.now());
    this.logger = deps?.logger;
  }

  async bootstrap(params: { sessionId: string; sessionFile: string }): Promise<BootstrapResult> {
    this.assertNotDisposed();

    const config = this.getConfig();
    const client = this.getClient();
    const source = this.sourceForSession(params.sessionId);

    const recentThoughts = await client.listRecent({
      limit: config.recentMessages,
      source,
    });

    const sessionThoughts = this.filterSessionThoughts(recentThoughts, params.sessionId);

    let maxTurn = -1;
    for (const thought of sessionThoughts) {
      const turn = thought.metadata?.turn;
      if (typeof turn === "number" && Number.isFinite(turn) && turn > maxTurn) {
        maxTurn = turn;
      }
    }

    this.sessionTurns.set(params.sessionId, maxTurn + 1);

    return {
      bootstrapped: true,
      importedMessages: sessionThoughts.length,
    };
  }

  async ingest(params: {
    sessionId: string;
    message: AgentMessage;
    isHeartbeat?: boolean;
  }): Promise<IngestResult> {
    this.assertNotDisposed();

    const client = this.getClient();
    const content = serializeContent(params.message.content).trim();
    if (content.length === 0) {
      return { ingested: false };
    }

    const metadata: OpenBrainThoughtMetadata = {
      sessionId: params.sessionId,
      turn: this.nextTurn(params.sessionId),
      role: normalizeRole(params.message.role),
      type: "message",
    };

    if (params.isHeartbeat === true) {
      metadata.isHeartbeat = true;
    }

    await client.createThought({
      content,
      source: this.sourceForSession(params.sessionId),
      metadata,
    });

    return { ingested: true };
  }

  async ingestBatch(params: {
    sessionId: string;
    messages: AgentMessage[];
    isHeartbeat?: boolean;
  }): Promise<IngestBatchResult> {
    this.assertNotDisposed();

    const maxConcurrency = 5;
    let ingestedCount = 0;
    for (let i = 0; i < params.messages.length; i += maxConcurrency) {
      const chunk = params.messages.slice(i, i + maxConcurrency);
      const results = await Promise.all(
        chunk.map((message) => {
          const ingestParams: {
            sessionId: string;
            message: AgentMessage;
            isHeartbeat?: boolean;
          } = {
            sessionId: params.sessionId,
            message,
          };
          if (params.isHeartbeat !== undefined) {
            ingestParams.isHeartbeat = params.isHeartbeat;
          }
          return this.ingest(ingestParams);
        }),
      );

      for (const result of results) {
        if (result.ingested) {
          ingestedCount += 1;
        }
      }
    }

    return { ingestedCount };
  }

  async assemble(params: {
    sessionId: string;
    messages: AgentMessage[];
    tokenBudget?: number;
  }): Promise<AssembleResult> {
    this.assertNotDisposed();

    const config = this.getConfig();
    const client = this.getClient();
    const source = this.sourceForSession(params.sessionId);

    const recentThoughts = this.filterSessionThoughts(
      await client.listRecent({
        limit: config.recentMessages,
        source,
      }),
      params.sessionId,
    );

    const semanticThoughts = await this.searchSemanticThoughts({
      client,
      source,
      config,
      sessionId: params.sessionId,
      messages: params.messages,
    });

    const mergedThoughts = this.mergeThoughts(recentThoughts, semanticThoughts);
    const mergedMessages =
      mergedThoughts.length > 0
        ? mergedThoughts.map((thought, index) => this.toAgentMessage(thought, index))
        : params.messages;

    const tokenBudget = params.tokenBudget;
    const budgetedMessages =
      typeof tokenBudget === "number" && tokenBudget > 0
        ? this.trimToBudget(mergedMessages, tokenBudget)
        : mergedMessages;

    return {
      messages: budgetedMessages,
      estimatedTokens: this.estimateTokensForMessages(budgetedMessages),
    };
  }

  async compact(params: {
    sessionId: string;
    sessionFile: string;
    tokenBudget?: number;
    force?: boolean;
    currentTokenCount?: number;
    compactionTarget?: "budget" | "threshold";
    customInstructions?: string;
    legacyParams?: Record<string, unknown>;
  }): Promise<CompactResult> {
    this.assertNotDisposed();

    const config = this.getConfig();
    const client = this.getClient();
    const source = this.sourceForSession(params.sessionId);

    const recentThoughts = this.filterSessionThoughts(
      await client.listRecent({
        limit: Math.max(config.recentMessages, config.subagentRecentMessages),
        source,
      }),
      params.sessionId,
    );

    if (recentThoughts.length === 0) {
      return {
        ok: true,
        compacted: false,
        reason: "no-session-context",
        result: {
          tokensBefore: 0,
          tokensAfter: 0,
        },
      };
    }

    const summarizedThoughts = this.selectSummaryThoughts(recentThoughts);
    const summary = this.buildSummary(
      params.customInstructions !== undefined
        ? {
            sessionId: params.sessionId,
            thoughts: summarizedThoughts,
            customInstructions: params.customInstructions,
          }
        : {
            sessionId: params.sessionId,
            thoughts: summarizedThoughts,
          },
    );

    const summaryTokens = estimateTextTokens(summary);
    const tokensBefore = this.estimateTokensForThoughts(summarizedThoughts);

    await client.createThought({
      content: summary,
      source,
      metadata: {
        sessionId: params.sessionId,
        turn: this.nextTurn(params.sessionId),
        role: "assistant",
        type: "summary",
      },
    });

    const summaryThoughtIds = Array.from(
      new Set(
        summarizedThoughts
          .map((thought) => thought.id.trim())
          .filter((id) => id.length > 0),
      ),
    );
    await Promise.all(summaryThoughtIds.map((thoughtId) => client.deleteThought(thoughtId)));

    return {
      ok: true,
      compacted: true,
      reason: "summary-archived",
      result: {
        summary,
        tokensBefore,
        tokensAfter: summaryTokens,
      },
    };
  }

  async prepareSubagentSpawn(params: {
    parentSessionKey: string;
    childSessionKey: string;
    ttlMs?: number;
  }): Promise<SubagentSpawnPreparation | undefined> {
    this.assertNotDisposed();

    const config = this.getConfig();
    const client = this.getClient();

    const parentThoughts = this.filterSessionThoughts(
      await client.listRecent({
        limit: config.subagentRecentMessages,
        source: this.sourceForSession(params.parentSessionKey),
      }),
      params.parentSessionKey,
    );

    const seedContent = this.buildSubagentSeedContent({
      parentSessionKey: params.parentSessionKey,
      childSessionKey: params.childSessionKey,
      thoughts: parentThoughts,
    });

    const createdThought = await client.createThought({
      content: seedContent,
      source: this.sourceForSession(params.childSessionKey),
      metadata: {
        sessionId: params.childSessionKey,
        role: "assistant",
        type: "summary",
        parentSessionId: params.parentSessionKey,
        ttlMs: params.ttlMs,
      },
    });

    this.subagentState.set(params.childSessionKey, {
      parentSessionKey: params.parentSessionKey,
      seedThoughtId: createdThought.id,
    });

    return {
      rollback: async () => {
        const state = this.subagentState.get(params.childSessionKey);
        this.subagentState.delete(params.childSessionKey);

        if (state?.seedThoughtId !== undefined && state.seedThoughtId.length > 0) {
          await client.deleteThought(state.seedThoughtId);
        }
      },
    };
  }

  async onSubagentEnded(params: {
    childSessionKey: string;
    reason: SubagentEndReason;
  }): Promise<void> {
    this.assertNotDisposed();

    const state = this.subagentState.get(params.childSessionKey);
    if (state === undefined) {
      return;
    }

    const client = this.getClient();
    const config = this.getConfig();

    const childThoughts = this.filterSessionThoughts(
      await client.listRecent({
        limit: config.subagentRecentMessages,
        source: this.sourceForSession(params.childSessionKey),
      }),
      params.childSessionKey,
    );

    const summary = this.buildSubagentResultSummary({
      childSessionKey: params.childSessionKey,
      reason: params.reason,
      thoughts: childThoughts,
    });

    await client.createThought({
      content: summary,
      source: this.sourceForSession(state.parentSessionKey),
      metadata: {
        sessionId: state.parentSessionKey,
        turn: this.nextTurn(state.parentSessionKey),
        role: "tool",
        type: "subagent-result",
        childSessionId: params.childSessionKey,
        reason: params.reason,
      },
    });

    this.subagentState.delete(params.childSessionKey);
  }

  async dispose(): Promise<void> {
    this.sessionTurns.clear();
    this.subagentState.clear();
    this.disposed = true;
  }

  private searchSemanticThoughts(params: {
    client: OpenBrainClientLike;
    source: string;
    config: ResolvedOpenBrainContextEngineConfig;
    sessionId: string;
    messages: AgentMessage[];
  }): Promise<OpenBrainThought[]> {
    const query = this.pickSemanticQuery(params.messages);
    if (query === undefined || query.length === 0 || params.config.semanticSearchLimit <= 0) {
      return Promise.resolve([]);
    }

    const request: OpenBrainSearchInput = {
      query,
      limit: params.config.semanticSearchLimit,
      source: params.source,
    };

    return params.client
      .search(request)
      .then((results) => this.filterSessionThoughts(results, params.sessionId))
      .catch((error) => {
        this.logger?.warn?.("OpenBrain semantic search failed", error);
        return [];
      });
  }

  private pickSemanticQuery(messages: AgentMessage[]): string | undefined {
    for (let i = messages.length - 1; i >= 0; i -= 1) {
      const message = messages[i];
      if (message === undefined) {
        continue;
      }
      if (normalizeRole(message.role) !== "user") {
        continue;
      }

      const content = serializeContent(message.content).trim();
      if (content.length > 0) {
        return content;
      }
    }

    for (let i = messages.length - 1; i >= 0; i -= 1) {
      const message = messages[i];
      if (message === undefined) {
        continue;
      }
      const content = serializeContent(message.content).trim();
      if (content.length > 0) {
        return content;
      }
    }

    return undefined;
  }

  private mergeThoughts(recentThoughts: OpenBrainThought[], semanticThoughts: OpenBrainThought[]): OpenBrainThought[] {
    const merged: OpenBrainThought[] = [];
    const seenIds = new Set<string>();
    const seenFingerprints = new Set<string>();

    for (const thought of [...recentThoughts, ...semanticThoughts]) {
      const id = thought.id.trim();
      const fingerprint = thoughtFingerprint(thought);

      if (id.length > 0 && seenIds.has(id)) {
        continue;
      }

      if (seenFingerprints.has(fingerprint)) {
        continue;
      }

      if (id.length > 0) {
        seenIds.add(id);
      }
      seenFingerprints.add(fingerprint);
      merged.push(thought);
    }

    return merged;
  }

  private filterSessionThoughts(thoughts: OpenBrainThought[], sessionId: string): OpenBrainThought[] {
    return thoughts.filter((thought) => {
      const thoughtSessionId = thought.metadata?.sessionId;
      if (typeof thoughtSessionId === "string" && thoughtSessionId.length > 0) {
        return thoughtSessionId === sessionId;
      }

      return thought.source === this.sourceForSession(sessionId);
    });
  }

  private toAgentMessage(thought: OpenBrainThought, index: number): AgentMessage {
    return {
      role: normalizeRole(thought.metadata?.role),
      content: thought.content,
      timestamp: thoughtTimestamp(thought, this.now() + index),
    };
  }

  private trimToBudget(messages: AgentMessage[], tokenBudget: number): AgentMessage[] {
    if (messages.length === 0 || tokenBudget <= 0) {
      return [];
    }

    let total = 0;
    const budgeted: AgentMessage[] = [];

    for (let i = messages.length - 1; i >= 0; i -= 1) {
      const message = messages[i];
      if (message === undefined) {
        continue;
      }
      const tokens = estimateTextTokens(serializeContent(message.content));
      if (total + tokens > tokenBudget) {
        break;
      }

      total += tokens;
      budgeted.unshift(message);
    }

    if (budgeted.length === 0) {
      const lastMessage = messages[messages.length - 1];
      return lastMessage === undefined ? [] : [lastMessage];
    }

    return budgeted;
  }

  private estimateTokensForMessages(messages: AgentMessage[]): number {
    return messages.reduce((total, message) => {
      return total + estimateTextTokens(serializeContent(message.content));
    }, 0);
  }

  private estimateTokensForThoughts(thoughts: OpenBrainThought[]): number {
    return thoughts.reduce((total, thought) => total + estimateTextTokens(thought.content), 0);
  }

  private buildSummary(params: {
    sessionId: string;
    thoughts: OpenBrainThought[];
    customInstructions?: string;
  }): string {
    const lines = params.thoughts.map((thought) => {
      const role = normalizeRole(thought.metadata?.role);
      const content = truncateLine(thought.content.replace(/\s+/g, " ").trim(), 180);
      return `- ${role}: ${content}`;
    });

    const header = `Context summary for session ${params.sessionId}`;
    const instruction =
      params.customInstructions !== undefined && params.customInstructions.trim().length > 0
        ? `Custom instructions: ${params.customInstructions.trim()}\n`
        : "";

    return `${header}\n${instruction}${lines.join("\n")}`;
  }

  private selectSummaryThoughts(thoughts: OpenBrainThought[]): OpenBrainThought[] {
    const ordered = [...thoughts].sort((a, b) => {
      return thoughtTimestamp(a, 0) - thoughtTimestamp(b, 0);
    });

    const maxLines = Math.min(ordered.length, 10);
    return ordered.slice(Math.max(ordered.length - maxLines, 0));
  }

  private buildSubagentSeedContent(params: {
    parentSessionKey: string;
    childSessionKey: string;
    thoughts: OpenBrainThought[];
  }): string {
    const lines = params.thoughts.slice(-5).map((thought) => {
      const role = normalizeRole(thought.metadata?.role);
      return `- ${role}: ${truncateLine(thought.content.replace(/\s+/g, " ").trim(), 160)}`;
    });

    const contextBlock = lines.length > 0 ? lines.join("\n") : "- (no prior context found)";

    return [
      `Subagent context seed`,
      `Parent session: ${params.parentSessionKey}`,
      `Child session: ${params.childSessionKey}`,
      contextBlock,
    ].join("\n");
  }

  private buildSubagentResultSummary(params: {
    childSessionKey: string;
    reason: SubagentEndReason;
    thoughts: OpenBrainThought[];
  }): string {
    const lines = params.thoughts.slice(-5).map((thought) => {
      const role = normalizeRole(thought.metadata?.role);
      return `- ${role}: ${truncateLine(thought.content.replace(/\s+/g, " ").trim(), 160)}`;
    });

    const contextBlock = lines.length > 0 ? lines.join("\n") : "- (no child messages found)";

    return [
      `Subagent ended (${params.reason})`,
      `Child session: ${params.childSessionKey}`,
      contextBlock,
    ].join("\n");
  }

  private sourceForSession(sessionId: string): string {
    return `${this.getConfig().source}:${sessionId}`;
  }

  private nextTurn(sessionId: string): number {
    const next = this.sessionTurns.get(sessionId) ?? 0;
    this.sessionTurns.set(sessionId, next + 1);
    return next;
  }

  private getClient(): OpenBrainClientLike {
    if (this.client !== undefined) {
      return this.client;
    }

    const config = this.getConfig();
    this.client =
      this.createClientFn?.(config) ??
      new OpenBrainClient({
        baseUrl: config.baseUrl,
        apiKey: config.apiKey,
      });

    return this.client;
  }

  private getConfig(): ResolvedOpenBrainContextEngineConfig {
    if (this.config !== undefined) {
      return this.config;
    }

    const raw = isRecord(this.rawConfig) ? this.rawConfig : {};

    const baseUrl = typeof raw.baseUrl === "string" ? raw.baseUrl.trim() : "";
    if (baseUrl.length === 0) {
      throw new OpenBrainConfigError("Missing required OpenBrain config: baseUrl");
    }

    const apiKey = typeof raw.apiKey === "string" ? raw.apiKey.trim() : "";
    if (apiKey.length === 0) {
      throw new OpenBrainConfigError("Missing required OpenBrain config: apiKey");
    }

    this.config = {
      baseUrl,
      apiKey,
      recentMessages: parsePositiveInteger(raw.recentMessages, 20),
      semanticSearchLimit: parsePositiveInteger(raw.semanticSearchLimit, 10),
      source: typeof raw.source === "string" && raw.source.trim().length > 0 ? raw.source.trim() : "openclaw",
      subagentRecentMessages: parsePositiveInteger(raw.subagentRecentMessages, 8),
    };

    return this.config;
  }

  private assertNotDisposed(): void {
    if (this.disposed) {
      throw new Error("OpenBrainContextEngine has already been disposed");
    }
  }
}