import { Injectable, Logger } from "@nestjs/common";
import { ConfigService } from "@nestjs/config";
import Docker from "dockerode";
import { PrismaService } from "../prisma/prisma.service";
import { CryptoService } from "../crypto/crypto.service";

const DEFAULT_DOCKER_SOCKET_PATH = "/var/run/docker.sock";
const DEFAULT_DOCKER_TCP_PORT = 2375;
const DEFAULT_OPENCLAW_IMAGE = "alpine/openclaw:latest";
const DEFAULT_OPENCLAW_NETWORK = "mosaic-internal";
const DEFAULT_OPENCLAW_PORT_RANGE_START = 19000;
const DEFAULT_MOSAIC_API_URL = "http://mosaic-api:3000/api";
const OPENCLAW_GATEWAY_PORT_KEY = "18789/tcp";
const OPENCLAW_STATE_PATH = "/home/node/.openclaw";
const CONTAINER_STOP_TIMEOUT_SECONDS = 10;

interface ContainerHandle {
  inspect(): Promise<DockerInspect>;
  start(): Promise<void>;
  stop(options?: { t?: number }): Promise<void>;
}

interface DockerInspect {
  Id?: string;
  State?: {
    Running?: boolean;
    Health?: {
      Status?: string;
    };
  };
  NetworkSettings?: {
    Ports?: Record<string, { HostPort?: string }[] | null>;
  };
  HostConfig?: {
    PortBindings?: Record<string, { HostPort?: string }[] | null>;
  };
}

interface UserContainerRecord {
  id: string;
  userId: string;
  containerId: string | null;
  containerName: string;
  gatewayPort: number | null;
  gatewayToken: string;
  status: string;
  lastActiveAt: Date | null;
  idleTimeoutMin: number;
}

interface ContainerLookup {
  containerId: string | null;
  containerName: string;
}

@Injectable()
export class ContainerLifecycleService {
  private readonly logger = new Logger(ContainerLifecycleService.name);
  private readonly docker: Docker;

  constructor(
    private readonly prisma: PrismaService,
    private readonly crypto: CryptoService,
    private readonly config: ConfigService
  ) {
    const dockerHost = this.config.get<string>("DOCKER_HOST");
    this.docker = this.createDockerClient(dockerHost);
  }

  // Ensure a user's container is running. Creates if needed, starts if stopped.
  // Returns the container's internal URL and gateway token.
  async ensureRunning(userId: string): Promise<{ url: string; token: string }> {
    const containerRecord = await this.getOrCreateContainerRecord(userId);
    const token = this.getGatewayToken(containerRecord.gatewayToken);
    const existingContainer = await this.resolveContainer(containerRecord);

    let container: ContainerHandle;
    if (existingContainer) {
      container = existingContainer;
      const inspect = await container.inspect();
      if (!inspect.State?.Running) {
        await container.start();
      }
    } else {
      const port = await this.findAvailableGatewayPort();
      container = await this.createContainer(containerRecord, token, port);
      await container.start();
    }

    const inspect = await container.inspect();
    const containerId = inspect.Id;
    if (!containerId) {
      throw new Error(
        `Docker inspect did not return container ID for ${containerRecord.containerName}`
      );
    }

    const gatewayPort = this.extractGatewayPort(inspect);
    if (!gatewayPort) {
      throw new Error(`Could not determine gateway port for ${containerRecord.containerName}`);
    }

    const now = new Date();
    await this.prisma.userContainer.update({
      where: { userId },
      data: {
        containerId,
        gatewayPort,
        status: "running",
        lastActiveAt: now,
      },
    });

    return {
      url: `http://${containerRecord.containerName}:${String(gatewayPort)}`,
      token,
    };
  }

  // Stop a user's container
  async stop(userId: string): Promise<void> {
    const containerRecord = await this.prisma.userContainer.findUnique({
      where: { userId },
    });

    if (!containerRecord) {
      return;
    }

    const container = await this.resolveContainer(containerRecord);
    if (container) {
      try {
        await container.stop({ t: CONTAINER_STOP_TIMEOUT_SECONDS });
      } catch (error) {
        if (!this.isDockerNotFound(error) && !this.isAlreadyStopped(error)) {
          throw error;
        }
      }
    }

    await this.prisma.userContainer.update({
      where: { userId },
      data: {
        status: "stopped",
        containerId: null,
        gatewayPort: null,
      },
    });
  }

  // Stop idle containers (called by cron/scheduler)
  async reapIdle(): Promise<{ stopped: string[] }> {
    const now = Date.now();
    const runningContainers = await this.prisma.userContainer.findMany({
      where: {
        status: "running",
        lastActiveAt: { not: null },
      },
      select: {
        userId: true,
        lastActiveAt: true,
        idleTimeoutMin: true,
      },
    });

    const stopped: string[] = [];
    for (const container of runningContainers) {
      const lastActiveAt = container.lastActiveAt;
      if (!lastActiveAt) {
        continue;
      }

      const idleLimitMs = container.idleTimeoutMin * 60 * 1000;
      if (now - lastActiveAt.getTime() < idleLimitMs) {
        continue;
      }

      try {
        await this.stop(container.userId);
        stopped.push(container.userId);
      } catch (error) {
        this.logger.warn(
          `Failed to stop idle container for user ${container.userId}: ${this.getErrorMessage(error)}`
        );
      }
    }

    return { stopped };
  }

  // Health check all running containers
  async healthCheckAll(): Promise<{ userId: string; healthy: boolean; error?: string }[]> {
    const runningContainers = await this.prisma.userContainer.findMany({
      where: {
        status: "running",
      },
      select: {
        userId: true,
        containerId: true,
        containerName: true,
      },
    });

    const results: { userId: string; healthy: boolean; error?: string }[] = [];
    for (const containerRecord of runningContainers) {
      const container = await this.resolveContainer(containerRecord);
      if (!container) {
        results.push({
          userId: containerRecord.userId,
          healthy: false,
          error: "Container not found",
        });
        continue;
      }

      try {
        const inspect = await container.inspect();
        const isRunning = inspect.State?.Running === true;
        const healthState = inspect.State?.Health?.Status;
        const healthy = isRunning && healthState !== "unhealthy";

        if (healthy) {
          results.push({
            userId: containerRecord.userId,
            healthy: true,
          });
          continue;
        }

        results.push({
          userId: containerRecord.userId,
          healthy: false,
          error:
            healthState === "unhealthy" ? "Container healthcheck failed" : "Container not running",
        });
      } catch (error) {
        results.push({
          userId: containerRecord.userId,
          healthy: false,
          error: this.getErrorMessage(error),
        });
      }
    }

    return results;
  }

  // Restart a container with fresh config (for config updates)
  async restart(userId: string): Promise<void> {
    await this.stop(userId);
    await this.ensureRunning(userId);
  }

  // Update lastActiveAt timestamp (called on each chat request)
  async touch(userId: string): Promise<void> {
    await this.prisma.userContainer.updateMany({
      where: { userId },
      data: {
        lastActiveAt: new Date(),
      },
    });
  }

  // Get container status for a user
  async getStatus(
    userId: string
  ): Promise<{ status: string; port?: number; lastActive?: Date } | null> {
    const container = await this.prisma.userContainer.findUnique({
      where: { userId },
      select: {
        status: true,
        gatewayPort: true,
        lastActiveAt: true,
      },
    });

    if (!container) {
      return null;
    }

    const status: { status: string; port?: number; lastActive?: Date } = {
      status: container.status,
    };

    if (container.gatewayPort !== null) {
      status.port = container.gatewayPort;
    }

    if (container.lastActiveAt !== null) {
      status.lastActive = container.lastActiveAt;
    }

    return status;
  }

  private createDockerClient(dockerHost?: string): Docker {
    if (!dockerHost || dockerHost.trim().length === 0) {
      return new Docker({ socketPath: DEFAULT_DOCKER_SOCKET_PATH });
    }

    if (dockerHost.startsWith("unix://")) {
      return new Docker({ socketPath: dockerHost.slice("unix://".length) });
    }

    if (dockerHost.startsWith("tcp://")) {
      const parsed = new URL(dockerHost.replace("tcp://", "http://"));
      return new Docker({
        host: parsed.hostname,
        port: this.parseInteger(parsed.port, DEFAULT_DOCKER_TCP_PORT),
        protocol: "http",
      });
    }

    if (dockerHost.startsWith("http://") || dockerHost.startsWith("https://")) {
      const parsed = new URL(dockerHost);
      const protocol = parsed.protocol.replace(":", "");
      return new Docker({
        host: parsed.hostname,
        port: this.parseInteger(parsed.port, DEFAULT_DOCKER_TCP_PORT),
        protocol: protocol === "https" ? "https" : "http",
      });
    }

    return new Docker({ socketPath: dockerHost });
  }

  private async getOrCreateContainerRecord(userId: string): Promise<UserContainerRecord> {
    const existingContainer = await this.prisma.userContainer.findUnique({
      where: { userId },
    });

    if (existingContainer) {
      return existingContainer;
    }

    const token = this.crypto.generateToken();
    const containerName = this.getContainerName(userId);
    return this.prisma.userContainer.create({
      data: {
        userId,
        containerName,
        gatewayToken: this.crypto.encrypt(token),
        status: "stopped",
      },
    });
  }

  private getContainerName(userId: string): string {
    return `mosaic-user-${userId}`;
  }

  private getVolumeName(userId: string): string {
    return `mosaic-user-${userId}-state`;
  }

  private getOpenClawImage(): string {
    return this.config.get<string>("OPENCLAW_IMAGE") ?? DEFAULT_OPENCLAW_IMAGE;
  }

  private getOpenClawNetwork(): string {
    return this.config.get<string>("OPENCLAW_NETWORK") ?? DEFAULT_OPENCLAW_NETWORK;
  }

  private getMosaicApiUrl(): string {
    return this.config.get<string>("MOSAIC_API_URL") ?? DEFAULT_MOSAIC_API_URL;
  }

  private getPortRangeStart(): number {
    return this.parseInteger(
      this.config.get<string>("OPENCLAW_PORT_RANGE_START"),
      DEFAULT_OPENCLAW_PORT_RANGE_START
    );
  }

  private async resolveContainer(record: ContainerLookup): Promise<ContainerHandle | null> {
    if (record.containerId) {
      const byId = this.docker.getContainer(record.containerId) as unknown as ContainerHandle;
      if (await this.containerExists(byId)) {
        return byId;
      }
    }

    const byName = await this.findContainerByName(record.containerName);
    if (byName) {
      return byName;
    }

    return null;
  }

  private async findContainerByName(containerName: string): Promise<ContainerHandle | null> {
    const containers = await this.docker.listContainers({
      all: true,
      filters: {
        name: [containerName],
      },
    });

    const match = containers.find((container) => {
      const names = container.Names;
      return names.some((name) => name === `/${containerName}` || name.includes(containerName));
    });

    if (!match?.Id) {
      return null;
    }

    return this.docker.getContainer(match.Id) as unknown as ContainerHandle;
  }

  private async containerExists(container: ContainerHandle): Promise<boolean> {
    try {
      await container.inspect();
      return true;
    } catch (error) {
      if (this.isDockerNotFound(error)) {
        return false;
      }

      throw error;
    }
  }

  private async createContainer(
    containerRecord: UserContainerRecord,
    token: string,
    gatewayPort: number
  ): Promise<ContainerHandle> {
    const container = await this.docker.createContainer({
      name: containerRecord.containerName,
      Image: this.getOpenClawImage(),
      Env: [
        `MOSAIC_API_URL=${this.getMosaicApiUrl()}`,
        `AGENT_TOKEN=${token}`,
        `AGENT_ID=${containerRecord.id}`,
      ],
      ExposedPorts: {
        [OPENCLAW_GATEWAY_PORT_KEY]: {},
      },
      HostConfig: {
        Binds: [`${this.getVolumeName(containerRecord.userId)}:${OPENCLAW_STATE_PATH}`],
        PortBindings: {
          [OPENCLAW_GATEWAY_PORT_KEY]: [{ HostPort: String(gatewayPort) }],
        },
        NetworkMode: this.getOpenClawNetwork(),
      },
    });

    return container as unknown as ContainerHandle;
  }

  private extractGatewayPort(inspect: DockerInspect): number | null {
    const networkPort = inspect.NetworkSettings?.Ports?.[OPENCLAW_GATEWAY_PORT_KEY]?.[0]?.HostPort;
    if (networkPort) {
      return this.parseInteger(networkPort, 0) || null;
    }

    const hostPort = inspect.HostConfig?.PortBindings?.[OPENCLAW_GATEWAY_PORT_KEY]?.[0]?.HostPort;
    if (hostPort) {
      return this.parseInteger(hostPort, 0) || null;
    }

    return null;
  }

  private async findAvailableGatewayPort(): Promise<number> {
    const usedPorts = await this.prisma.userContainer.findMany({
      where: {
        gatewayPort: { not: null },
      },
      select: {
        gatewayPort: true,
      },
    });

    const takenPorts = new Set<number>();
    for (const entry of usedPorts) {
      if (entry.gatewayPort !== null) {
        takenPorts.add(entry.gatewayPort);
      }
    }

    let candidate = this.getPortRangeStart();
    while (takenPorts.has(candidate)) {
      candidate += 1;
    }

    return candidate;
  }

  private getGatewayToken(storedToken: string): string {
    if (this.crypto.isEncrypted(storedToken)) {
      return this.crypto.decrypt(storedToken);
    }

    return storedToken;
  }

  private parseInteger(value: string | undefined, fallback: number): number {
    if (!value) {
      return fallback;
    }

    const parsed = Number.parseInt(value, 10);
    return Number.isFinite(parsed) ? parsed : fallback;
  }

  private isDockerNotFound(error: unknown): boolean {
    return this.getDockerStatusCode(error) === 404;
  }

  private isAlreadyStopped(error: unknown): boolean {
    return this.getDockerStatusCode(error) === 304;
  }

  private getDockerStatusCode(error: unknown): number | null {
    if (typeof error !== "object" || error === null || !("statusCode" in error)) {
      return null;
    }

    const statusCode = error.statusCode;
    return typeof statusCode === "number" ? statusCode : null;
  }

  private getErrorMessage(error: unknown): string {
    if (error instanceof Error) {
      return error.message;
    }

    return "Unknown error";
  }
}