import {
  ChannelType,
  EmbedBuilder,
  PermissionFlagsBits,
  type Emoji,
  type GuildBasedChannel,
  type Message,
  type PartialMessage,
  type PartialMessageReaction,
  type MessageReaction,
  type TextChannel
} from 'discord.js';
import type { PrismaClient, StarboardConfig } from '@prisma/client';
import { t, type Locale } from '@nexumi/shared';
import { ensureGuild } from '../../guild.js';
import { logger } from '../../logger.js';
import type { BotContext } from '../../types.js';
import { getGuildLocale } from '../../i18n.js';

export async function getStarboardConfig(prisma: PrismaClient, guildId: string) {
  await ensureGuild(prisma, guildId);
  let config = await prisma.starboardConfig.findUnique({ where: { guildId } });
  if (!config) {
    config = await prisma.starboardConfig.create({ data: { guildId } });
  }
  return config;
}

export async function updateStarboardConfig(
  prisma: PrismaClient,
  guildId: string,
  data: {
    enabled: boolean;
    channelId: string;
    emoji: string;
    threshold: number;
    allowSelfStar: boolean;
  }
) {
  await ensureGuild(prisma, guildId);
  return prisma.starboardConfig.upsert({
    where: { guildId },
    update: data,
    create: { guildId, ...data }
  });
}

export function emojiMatches(configEmoji: string, reactionEmoji: Emoji): boolean {
  if (reactionEmoji.id) {
    return (
      configEmoji === reactionEmoji.identifier ||
      configEmoji === reactionEmoji.toString() ||
      configEmoji === `<:${reactionEmoji.name}:${reactionEmoji.id}>` ||
      configEmoji === `<a:${reactionEmoji.name}:${reactionEmoji.id}>`
    );
  }
  return configEmoji === reactionEmoji.name || configEmoji === reactionEmoji.toString();
}

export function shouldIgnoreMessage(message: Message, config: StarboardConfig): boolean {
  if (message.author.bot) {
    return true;
  }
  if (!message.guild || !message.channel.isTextBased() || message.channel.isDMBased()) {
    return true;
  }
  if ('nsfw' in message.channel && message.channel.nsfw) {
    return true;
  }
  if (config.ignoredChannelIds.includes(message.channel.id)) {
    return true;
  }
  if (config.channelId && message.channel.id === config.channelId) {
    return true;
  }
  return false;
}

export function botCanPostStarboard(channel: GuildBasedChannel, meId: string): channel is TextChannel {
  if (!channel.isTextBased() || channel.isDMBased()) {
    return false;
  }
  if (
    channel.type !== ChannelType.GuildText &&
    channel.type !== ChannelType.GuildAnnouncement
  ) {
    return false;
  }
  const permissions = channel.permissionsFor(meId);
  if (!permissions) {
    return false;
  }
  return (
    permissions.has(PermissionFlagsBits.ViewChannel) &&
    permissions.has(PermissionFlagsBits.SendMessages) &&
    permissions.has(PermissionFlagsBits.EmbedLinks)
  );
}

export async function countMatchingStars(
  message: Message,
  config: StarboardConfig
): Promise<number> {
  const reaction = message.reactions.cache.find((r) => emojiMatches(config.emoji, r.emoji));
  if (!reaction || reaction.count === 0) {
    return 0;
  }

  const fetchedReaction = reaction.partial ? await reaction.fetch() : reaction;
  const users = await fetchedReaction.users.fetch();
  let count = 0;
  for (const [, user] of users) {
    if (user.bot) {
      continue;
    }
    if (!config.allowSelfStar && user.id === message.author.id) {
      continue;
    }
    count++;
  }
  return count;
}

function resolveImageUrl(message: Message): string | undefined {
  const attachment = message.attachments.find((a) => {
    const type = a.contentType ?? '';
    return type.startsWith('image/') || /\.(png|jpe?g|gif|webp)$/i.test(a.name);
  });
  if (attachment) {
    return attachment.url;
  }
  const embedImage = message.embeds.find((e) => e.image?.url)?.image?.url;
  return embedImage ?? undefined;
}

function authorDisplayName(message: Message): string {
  return message.member?.displayName || message.author.displayName || message.author.username;
}

export function buildStarboardEmbed(
  message: Message,
  starCount: number,
  config: StarboardConfig,
  locale: Locale
): EmbedBuilder {
  const content = message.content?.trim() || t(locale, 'starboard.noContent');
  const embed = new EmbedBuilder()
    .setColor(0x6366f1)
    .setAuthor({
      name: authorDisplayName(message),
      iconURL: message.author.displayAvatarURL()
    })
    .setDescription(content.slice(0, 4096))
    .addFields({
      name: t(locale, 'starboard.field.stars'),
      value: `${config.emoji} **${starCount}**`,
      inline: true
    })
    .addFields({
      name: t(locale, 'starboard.field.source'),
      value: `[${t(locale, 'starboard.jumpLink')}](${message.url})`,
      inline: true
    })
    .setTimestamp(message.createdAt);

  const imageUrl = resolveImageUrl(message);
  if (imageUrl) {
    embed.setImage(imageUrl);
  }

  return embed;
}

async function fetchStarboardTextChannel(
  context: BotContext,
  channelId: string
): Promise<TextChannel | null> {
  const channel = await context.client.channels.fetch(channelId).catch(() => null);
  if (!channel || !channel.isTextBased() || channel.isDMBased()) {
    return null;
  }
  return channel as TextChannel;
}

async function removeStarboardEntry(context: BotContext, entryId: string): Promise<void> {
  const entry = await context.prisma.starboardEntry.findUnique({ where: { id: entryId } });
  if (!entry) {
    return;
  }

  try {
    const config = await getStarboardConfig(context.prisma, entry.guildId);
    if (config.channelId) {
      const channel = await fetchStarboardTextChannel(context, config.channelId);
      if (channel) {
        const starboardMessage = await channel.messages
          .fetch(entry.starboardMessageId)
          .catch(() => null);
        await starboardMessage?.delete().catch(() => undefined);
      }
    }
  } catch (error) {
    logger.warn({ error, entryId }, 'Failed to delete starboard message');
  }

  await context.prisma.starboardEntry.delete({ where: { id: entryId } }).catch(() => undefined);
}

export async function removeStarboardEntryBySource(
  context: BotContext,
  guildId: string,
  sourceMessageId: string
): Promise<void> {
  const entry = await context.prisma.starboardEntry.findUnique({
    where: {
      guildId_sourceMessageId: { guildId, sourceMessageId }
    }
  });
  if (entry) {
    await removeStarboardEntry(context, entry.id);
  }
}

async function createOrRecreateStarboardPost(
  context: BotContext,
  message: Message,
  config: StarboardConfig,
  locale: Locale,
  starCount: number,
  starboardChannel: TextChannel,
  existingId?: string
): Promise<void> {
  const embed = buildStarboardEmbed(message, starCount, config, locale);
  const starboardMessage = await starboardChannel.send({ embeds: [embed] });

  if (existingId) {
    await context.prisma.starboardEntry.update({
      where: { id: existingId },
      data: {
        starboardMessageId: starboardMessage.id,
        starCount,
        sourceChannelId: message.channel.id
      }
    });
    return;
  }

  try {
    await context.prisma.starboardEntry.create({
      data: {
        guildId: message.guild!.id,
        sourceChannelId: message.channel.id,
        sourceMessageId: message.id,
        starboardMessageId: starboardMessage.id,
        starCount
      }
    });
  } catch (error) {
    // Race: another reaction created the row first — keep the newer post, drop ours.
    logger.warn({ error, messageId: message.id }, 'Starboard entry create raced; cleaning up');
    await starboardMessage.delete().catch(() => undefined);
    const winner = await context.prisma.starboardEntry.findUnique({
      where: {
        guildId_sourceMessageId: {
          guildId: message.guild!.id,
          sourceMessageId: message.id
        }
      }
    });
    if (winner) {
      await context.prisma.starboardEntry.update({
        where: { id: winner.id },
        data: { starCount }
      });
      const existingMsg = await starboardChannel.messages
        .fetch(winner.starboardMessageId)
        .catch(() => null);
      if (existingMsg) {
        await existingMsg.edit({ embeds: [embed] }).catch(() => undefined);
      }
    }
  }
}

export async function processStarboardMessage(context: BotContext, message: Message): Promise<void> {
  if (!message.guild) {
    return;
  }

  const config = await getStarboardConfig(context.prisma, message.guild.id);
  if (!config.enabled || !config.channelId) {
    return;
  }
  if (shouldIgnoreMessage(message, config)) {
    return;
  }

  const starCount = await countMatchingStars(message, config);
  const locale = await getGuildLocale(context.prisma, message.guild.id);
  const existing = await context.prisma.starboardEntry.findUnique({
    where: {
      guildId_sourceMessageId: {
        guildId: message.guild.id,
        sourceMessageId: message.id
      }
    }
  });

  if (starCount < config.threshold) {
    if (existing) {
      await removeStarboardEntry(context, existing.id);
    }
    return;
  }

  const starboardChannel = await fetchStarboardTextChannel(context, config.channelId);
  if (!starboardChannel) {
    logger.warn({ guildId: message.guild.id, channelId: config.channelId }, 'Starboard channel missing');
    return;
  }

  const embed = buildStarboardEmbed(message, starCount, config, locale);

  if (existing) {
    try {
      const starboardMessage = await starboardChannel.messages.fetch(existing.starboardMessageId);
      await starboardMessage.edit({ embeds: [embed] });
      await context.prisma.starboardEntry.update({
        where: { id: existing.id },
        data: { starCount }
      });
    } catch (error) {
      logger.warn({ error, messageId: message.id }, 'Starboard message missing; recreating');
      await createOrRecreateStarboardPost(
        context,
        message,
        config,
        locale,
        starCount,
        starboardChannel,
        existing.id
      );
    }
    return;
  }

  await createOrRecreateStarboardPost(
    context,
    message,
    config,
    locale,
    starCount,
    starboardChannel
  );
}

export async function processStarboardReaction(
  context: BotContext,
  reaction: MessageReaction | PartialMessageReaction
): Promise<void> {
  if (reaction.partial) {
    await reaction.fetch();
  }

  const message = reaction.message;
  if (message.partial) {
    await message.fetch();
  }
  if (!message.guild || !message.author) {
    return;
  }

  const config = await getStarboardConfig(context.prisma, message.guild.id);
  if (!config.enabled || !config.channelId) {
    return;
  }
  if (!emojiMatches(config.emoji, reaction.emoji)) {
    return;
  }

  await processStarboardMessage(context, message as Message);
}

export async function processStarboardSourceDelete(
  context: BotContext,
  message: Message | PartialMessage
): Promise<void> {
  if (!message.guildId || !message.id) {
    return;
  }
  await removeStarboardEntryBySource(context, message.guildId, message.id);
}

export async function processStarboardSourceUpdate(
  context: BotContext,
  message: Message | PartialMessage
): Promise<void> {
  if (!message.guildId || !message.id) {
    return;
  }

  const entry = await context.prisma.starboardEntry.findUnique({
    where: {
      guildId_sourceMessageId: {
        guildId: message.guildId,
        sourceMessageId: message.id
      }
    }
  });
  if (!entry) {
    return;
  }

  const full = message.partial ? await message.fetch().catch(() => null) : message;
  if (!full || !full.guild) {
    return;
  }

  await processStarboardMessage(context, full as Message);
}