import { eq, and, sql } from 'drizzle-orm';
import { type LibSQLDatabase } from 'drizzle-orm/libsql';
import type * as schema from '../schema/index';
import { channels, contentItems } from '../schema/index';
import type { Channel, Platform, MonitoringMode } from '../../types/index';

// ── Types ──

/** Fields needed to create a new channel (auto-generated fields excluded). */
export type CreateChannelData = Omit<
  Channel,
  'id' | 'createdAt' | 'updatedAt' | 'lastCheckedAt' | 'lastCheckStatus' | 'monitoringMode'
> & { monitoringMode?: Channel['monitoringMode'] };

/** Fields that can be updated on an existing channel. */
export type UpdateChannelData = Partial<
  Pick<Channel, 'name' | 'checkInterval' | 'monitoringEnabled' | 'imageUrl' | 'formatProfileId' | 'lastCheckedAt' | 'lastCheckStatus' | 'monitoringMode'>
>;

type Db = LibSQLDatabase<typeof schema>;

// ── Repository Functions ──

/** Insert a new channel and return the created row. */
export async function createChannel(
  db: Db,
  data: CreateChannelData
): Promise<Channel> {
  const result = await db
    .insert(channels)
    .values({
      name: data.name,
      platform: data.platform,
      platformId: data.platformId,
      url: data.url,
      monitoringEnabled: data.monitoringEnabled,
      checkInterval: data.checkInterval,
      imageUrl: data.imageUrl,
      metadata: data.metadata,
      formatProfileId: data.formatProfileId,
      monitoringMode: data.monitoringMode ?? 'all',
    })
    .returning();

  return mapRow(result[0]);
}

/** Get a channel by ID. Returns null if not found. */
export async function getChannelById(
  db: Db,
  id: number
): Promise<Channel | null> {
  const rows = await db
    .select()
    .from(channels)
    .where(eq(channels.id, id))
    .limit(1);

  return rows.length > 0 ? mapRow(rows[0]) : null;
}

/** Get all channels, ordered by name. */
export async function getAllChannels(db: Db): Promise<Channel[]> {
  const rows = await db.select().from(channels).orderBy(channels.name);
  return rows.map(mapRow);
}

/** Get all channels with monitoring enabled. */
export async function getEnabledChannels(db: Db): Promise<Channel[]> {
  const rows = await db
    .select()
    .from(channels)
    .where(eq(channels.monitoringEnabled, true))
    .orderBy(channels.name);

  return rows.map(mapRow);
}

/** Update specific fields on a channel. Sets updatedAt to now. Returns updated row or null. */
export async function updateChannel(
  db: Db,
  id: number,
  data: UpdateChannelData
): Promise<Channel | null> {
  const result = await db
    .update(channels)
    .set({
      ...data,
      updatedAt: sql`(datetime('now'))`,
    })
    .where(eq(channels.id, id))
    .returning();

  return result.length > 0 ? mapRow(result[0]) : null;
}

/**
 * Change a channel's monitoring mode and cascade the `monitored` flag to all existing content items.
 *
 * Cascade logic:
 * - 'all' or 'existing' → existing items become monitored (true)
 * - 'future' or 'none' → existing items become unmonitored (false)
 *
 * Also syncs `monitoringEnabled`: mode !== 'none' → enabled (per D022).
 * Returns updated channel or null if not found.
 */
export async function setMonitoringMode(
  db: Db,
  id: number,
  mode: MonitoringMode
): Promise<Channel | null> {
  // Step 1: Cascade monitored flag to all content items for this channel
  const cascadeMonitored = mode === 'all' || mode === 'existing';
  await db
    .update(contentItems)
    .set({
      monitored: cascadeMonitored,
      updatedAt: sql`(datetime('now'))`,
    })
    .where(eq(contentItems.channelId, id));

  // Step 2: Update the channel's monitoringMode and monitoringEnabled
  const result = await db
    .update(channels)
    .set({
      monitoringMode: mode,
      monitoringEnabled: mode !== 'none',
      updatedAt: sql`(datetime('now'))`,
    })
    .where(eq(channels.id, id))
    .returning();

  return result.length > 0 ? mapRow(result[0]) : null;
}

/** Delete a channel by ID. Returns true if a row was deleted. */
export async function deleteChannel(
  db: Db,
  id: number
): Promise<boolean> {
  const result = await db
    .delete(channels)
    .where(eq(channels.id, id))
    .returning({ id: channels.id });

  return result.length > 0;
}

/** Find a channel by platform and platformId (for duplicate detection). */
export async function getChannelByPlatformId(
  db: Db,
  platform: string,
  platformId: string
): Promise<Channel | null> {
  const rows = await db
    .select()
    .from(channels)
    .where(
      and(
        eq(channels.platform, platform),
        eq(channels.platformId, platformId)
      )
    )
    .limit(1);

  return rows.length > 0 ? mapRow(rows[0]) : null;
}

// ── Row Mapping ──

/**
 * Map a raw Drizzle row to the Channel domain type.
 * Ensures boolean and nullable fields are correctly typed.
 */
function mapRow(row: typeof channels.$inferSelect): Channel {
  return {
    id: row.id,
    name: row.name,
    platform: row.platform as Platform,
    platformId: row.platformId,
    url: row.url,
    monitoringEnabled: row.monitoringEnabled,
    checkInterval: row.checkInterval,
    imageUrl: row.imageUrl,
    metadata: row.metadata as Record<string, unknown> | null,
    formatProfileId: row.formatProfileId,
    monitoringMode: (row.monitoringMode ?? 'all') as Channel['monitoringMode'],
    createdAt: row.createdAt,
    updatedAt: row.updatedAt,
    lastCheckedAt: row.lastCheckedAt,
    lastCheckStatus: row.lastCheckStatus as Channel['lastCheckStatus'],
  };
}