import {
  Command,
  CommanderError,
  InvalidArgumentError,
  Option,
} from 'commander';

import { assertRedisHealthy, createRedisClient } from './redis-connection.js';
import {
  RedisTaskRepository,
  type ClaimTaskInput,
  type CompleteTaskInput,
  type RedisTaskClient,
} from './task-repository.js';
import { TASK_LANES, TASK_PRIORITIES, TASK_STATUSES } from './task.js';
import type {
  CreateTaskInput,
  TaskLane,
  TaskListFilters,
  TaskPriority,
  TaskStatus,
} from '@mosaic/types';

export type QueueRepository = Pick<
  RedisTaskRepository,
  'create' | 'list' | 'get' | 'claim' | 'release' | 'complete'
>;

export interface QueueRepositorySession {
  readonly repository: QueueRepository;
  readonly close: () => Promise<void>;
}

export interface QueueCliDependencies {
  readonly openSession: () => Promise<QueueRepositorySession>;
  readonly stdout: (line: string) => void;
  readonly stderr: (line: string) => void;
}

interface CreateCommandOptions {
  readonly title: string;
  readonly description?: string;
  readonly priority?: TaskPriority;
  readonly lane?: TaskLane;
  readonly dependency?: string[];
}

interface ListCommandOptions {
  readonly project?: string;
  readonly mission?: string;
  readonly status?: TaskStatus;
}

interface ClaimCommandOptions {
  readonly agent: string;
  readonly ttl: number;
}

interface ReleaseCommandOptions {
  readonly agent?: string;
}

interface CompleteCommandOptions {
  readonly agent?: string;
  readonly summary?: string;
}

interface ClosableRedisTaskClient extends RedisTaskClient {
  ping(): Promise<string>;
  quit(): Promise<string>;
}

const DEFAULT_DEPENDENCIES: QueueCliDependencies = {
  openSession: openRedisSession,
  stdout: (line: string) => {
    console.log(line);
  },
  stderr: (line: string) => {
    console.error(line);
  },
};

const PRIORITY_SET = new Set<TaskPriority>(TASK_PRIORITIES);
const LANE_SET = new Set<TaskLane>(TASK_LANES);
const STATUS_SET = new Set<TaskStatus>(TASK_STATUSES);

export function buildQueueCli(
  dependencyOverrides: Partial<QueueCliDependencies> = {},
): Command {
  const dependencies = resolveDependencies(dependencyOverrides);
  const program = new Command();
  program
    .name('mosaic')
    .description('mosaic queue command line interface')
    .exitOverride();

  program.configureOutput({
    writeOut: (output: string) => dependencies.stdout(output.trimEnd()),
    writeErr: (output: string) => dependencies.stderr(output.trimEnd()),
  });

  const queue = program.command('queue').description('Manage queue tasks');

  queue
    .command('create <project> <mission> <taskId>')
    .description('Create a queue task')
    .requiredOption('--title <title>', 'Task title')
    .option('--description <description>', 'Task description')
    .addOption(
      new Option('--priority <priority>', 'Task priority')
        .choices(TASK_PRIORITIES)
        .argParser(parsePriority),
    )
    .addOption(
      new Option('--lane <lane>', 'Task lane').choices(TASK_LANES).argParser(parseLane),
    )
    .option('--dependency <taskIds...>', 'Task dependencies')
    .action(
      async (
        project: string,
        mission: string,
        taskId: string,
        options: CreateCommandOptions,
      ) => {
        await withSession(dependencies, async (repository) => {
          const payload: CreateTaskInput = {
            project,
            mission,
            taskId,
            title: options.title,
            description: options.description,
            priority: options.priority,
            dependencies: options.dependency,
            lane: options.lane,
          };
          const task = await repository.create(payload);
          dependencies.stdout(JSON.stringify(task, null, 2));
        });
      },
    );

  queue
    .command('list')
    .description('List queue tasks')
    .option('--project <project>', 'Filter by project')
    .option('--mission <mission>', 'Filter by mission')
    .addOption(
      new Option('--status <status>', 'Filter by status')
        .choices(TASK_STATUSES)
        .argParser(parseStatus),
    )
    .action(async (options: ListCommandOptions) => {
      await withSession(dependencies, async (repository) => {
        const filters: TaskListFilters = {
          project: options.project,
          mission: options.mission,
          status: options.status,
        };
        const tasks = await repository.list(filters);
        dependencies.stdout(JSON.stringify(tasks, null, 2));
      });
    });

  queue
    .command('show <taskId>')
    .description('Show a single queue task')
    .action(async (taskId: string) => {
      await withSession(dependencies, async (repository) => {
        const task = await repository.get(taskId);

        if (task === null) {
          throw new Error(`Task ${taskId} was not found.`);
        }

        dependencies.stdout(JSON.stringify(task, null, 2));
      });
    });

  queue
    .command('claim <taskId>')
    .description('Claim a pending task')
    .requiredOption('--agent <agentId>', 'Agent identifier')
    .requiredOption('--ttl <seconds>', 'Claim TTL in seconds', parsePositiveInteger)
    .action(async (taskId: string, options: ClaimCommandOptions) => {
      await withSession(dependencies, async (repository) => {
        const claimInput: ClaimTaskInput = {
          agentId: options.agent,
          ttlSeconds: options.ttl,
        };
        const task = await repository.claim(taskId, claimInput);
        dependencies.stdout(JSON.stringify(task, null, 2));
      });
    });

  queue
    .command('release <taskId>')
    .description('Release a claimed task back to pending')
    .option('--agent <agentId>', 'Expected owner agent id')
    .action(async (taskId: string, options: ReleaseCommandOptions) => {
      await withSession(dependencies, async (repository) => {
        const task = await repository.release(taskId, {
          agentId: options.agent,
        });
        dependencies.stdout(JSON.stringify(task, null, 2));
      });
    });

  queue
    .command('complete <taskId>')
    .description('Complete a claimed task')
    .option('--agent <agentId>', 'Expected owner agent id')
    .option('--summary <summary>', 'Optional completion summary')
    .action(async (taskId: string, options: CompleteCommandOptions) => {
      await withSession(dependencies, async (repository) => {
        const completeInput: CompleteTaskInput = {
          agentId: options.agent,
          summary: options.summary,
        };
        const task = await repository.complete(taskId, completeInput);
        dependencies.stdout(JSON.stringify(task, null, 2));
      });
    });

  return program;
}

export async function runQueueCli(
  argv: string[] = process.argv,
  dependencyOverrides: Partial<QueueCliDependencies> = {},
): Promise<number> {
  const dependencies = resolveDependencies(dependencyOverrides);
  const program = buildQueueCli(dependencies);

  try {
    await program.parseAsync(argv, {
      from: 'node',
    });
    return 0;
  } catch (error) {
    if (error instanceof CommanderError) {
      if (error.code === 'commander.helpDisplayed') {
        return 0;
      }

      if (error.code.startsWith('commander.')) {
        return error.exitCode;
      }
    }

    dependencies.stderr(formatError(error));
    return 1;
  }
}

async function openRedisSession(): Promise<QueueRepositorySession> {
  const redisClient = createRedisClient<ClosableRedisTaskClient>();

  try {
    await assertRedisHealthy(redisClient);

    return {
      repository: new RedisTaskRepository({
        client: redisClient,
      }),
      close: async () => {
        await redisClient.quit();
      },
    };
  } catch (error) {
    await redisClient.quit();
    throw error;
  }
}

async function withSession(
  dependencies: QueueCliDependencies,
  action: (repository: QueueRepository) => Promise<void>,
): Promise<void> {
  const session = await dependencies.openSession();

  try {
    await action(session.repository);
  } finally {
    await session.close();
  }
}

function resolveDependencies(
  overrides: Partial<QueueCliDependencies>,
): QueueCliDependencies {
  const openSession = overrides.openSession ?? DEFAULT_DEPENDENCIES.openSession;
  const stdout = overrides.stdout ?? DEFAULT_DEPENDENCIES.stdout;
  const stderr = overrides.stderr ?? DEFAULT_DEPENDENCIES.stderr;

  return {
    openSession: () => openSession(),
    stdout: (line: string) => stdout(line),
    stderr: (line: string) => stderr(line),
  };
}

function parsePositiveInteger(value: string): number {
  const parsed = Number.parseInt(value, 10);

  if (!Number.isInteger(parsed) || parsed <= 0) {
    throw new InvalidArgumentError(`Expected a positive integer, received "${value}"`);
  }

  return parsed;
}

function parsePriority(value: string): TaskPriority {
  if (!PRIORITY_SET.has(value as TaskPriority)) {
    throw new InvalidArgumentError(
      `Expected one of ${TASK_PRIORITIES.join(', ')}, received "${value}"`,
    );
  }

  return value as TaskPriority;
}

function parseLane(value: string): TaskLane {
  if (!LANE_SET.has(value as TaskLane)) {
    throw new InvalidArgumentError(
      `Expected one of ${TASK_LANES.join(', ')}, received "${value}"`,
    );
  }

  return value as TaskLane;
}

function parseStatus(value: string): TaskStatus {
  if (!STATUS_SET.has(value as TaskStatus)) {
    throw new InvalidArgumentError(
      `Expected one of ${TASK_STATUSES.join(', ')}, received "${value}"`,
    );
  }

  return value as TaskStatus;
}

function formatError(error: unknown): string {
  return error instanceof Error ? error.message : String(error);
}