import {
  type Client,
  type ChatInputCommandInteraction,
  type AutocompleteInteraction,
  type ButtonInteraction,
  type ApplicationCommandNonOptionsData,
  BaseInteraction,
} from "discord.js";

import { HaltExecution } from "./errors";
import { type Option, type InferOptions, OPTION_TYPES } from "./options";
import { KittenComponent } from "./components";
import { Command, CommandBuilder, SubcommandGroupBuilder } from "./commands";
import { baseLogger, type KittenLogger } from "./logger";

export interface KittenOptions {
  logger?: KittenLogger;
}

export class Kitten {
  private commands = new Map<string, Command | SubcommandGroupBuilder<any>>();
  private components = new Map<string, KittenComponent>();
  private logger: KittenLogger;

  constructor(
    private client: Client,
    options: KittenOptions = {},
  ) {
    this.client.on("interactionCreate", this.handleInteraction.bind(this));
    this.logger = options.logger ?? baseLogger;
  }

  builder() {
    return new CommandBuilder();
  }

  command<O extends Record<string, Option<any, any>>>(
    name: string,
    config: {
      description: string;
      options?: O;
      run: (
        interaction: ChatInputCommandInteraction,
        args: InferOptions<O>,
      ) => Promise<void> | void;
    },
  ): Command;

  command(name: string, config: { description: string }): SubcommandGroupBuilder<{}>;
  command(name: string, config: any): any {
    return this.builder().command(name, config);
  }

  button<O extends Record<string, Option<any, any>>>(
    name: string,
    config: {
      options?: O;
      run: (interaction: ButtonInteraction, args: InferOptions<O>) => Promise<void> | void;
    },
  ): KittenComponent {
    return new KittenComponent(name, config);
  }

  register(registry: {
    commands?: (Command | SubcommandGroupBuilder<any>)[];
    components?: KittenComponent[];
  }) {
    registry.commands?.forEach((cmd) => this.commands.set(cmd.name, cmd));
    registry.components?.forEach((comp) => this.components.set(comp.name, comp));
  }

  private async handleInteraction(interaction: BaseInteraction) {
    // commands
    if (interaction.isChatInputCommand()) await this.routeCommand(interaction);
    else if (interaction.isAutocomplete()) await this.routeAutocomplete(interaction);

    // components
    else if (interaction.isButton()) await this.routeButton(interaction);
  }

  private async routeCommand(interaction: ChatInputCommandInteraction) {
    const entry = this.commands.get(interaction.commandName);
    if (!entry) return;

    if (entry instanceof SubcommandGroupBuilder) {
      const groupName = interaction.options.getSubcommandGroup(false);
      const subName = interaction.options.getSubcommand(false);

      if (groupName) {
        const group = entry.groups[groupName];
        if (!group) return;
        const subcommand = group.subcommands[subName ?? ""];
        if (!subcommand) return;

        await this.executeWithMiddlewares(
          interaction,
          entry.middlewares,
          subcommand.config.run,
          subcommand.config.options,
        );
      } else if (subName) {
        const subcommand = entry.subcommands[subName];
        if (!subcommand) return;

        await this.executeWithMiddlewares(
          interaction,
          entry.middlewares,
          subcommand.config.run,
          subcommand.config.options,
        );
      }
    } else {
      await this.executeWithMiddlewares(
        interaction,
        entry.middlewares,
        entry.config.run,
        entry.config.options,
      );
    }
  }

  private async executeWithMiddlewares(
    interaction: ChatInputCommandInteraction,
    middlewares: Function[],
    run: Function,
    optionsSchema?: Record<string, Option<any, any>>,
  ) {
    try {
      let context = {};
      for (const mw of middlewares) {
        const result = await mw(interaction, context);
        if (result) context = { ...context, ...result };
      }

      const args = this.parseSlashOptions(interaction, optionsSchema);
      await run(interaction, args, context);
    } catch (err) {
      // TODO)) custom error handlers
      if (err instanceof HaltExecution) return;

      this.logger.error(`unhandled error executing command ${interaction.commandName}:`, {
        error: err instanceof Error ? err.stack : String(err),
        command: interaction.commandName,
        user: interaction.user.id,
      });

      if (!interaction.replied && !interaction.deferred) {
        await interaction
          .reply({ content: "an error occurred while executing this command.", ephemeral: true })
          .catch(() => null);
      }
    }
  }

  private async routeAutocomplete(interaction: AutocompleteInteraction) {
    const entry = this.commands.get(interaction.commandName);
    if (!entry) return;

    const focused = interaction.options.getFocused(true);
    let optionsSchema: Record<string, Option<any, any>> | undefined;

    if (entry instanceof SubcommandGroupBuilder) {
      const groupName = interaction.options.getSubcommandGroup(false);
      const subName = interaction.options.getSubcommand(false);

      if (groupName && subName)
        optionsSchema = entry.groups[groupName]?.subcommands[subName]?.config.options;
      else if (subName) optionsSchema = entry.subcommands[subName]?.config.options;
    } else {
      optionsSchema = entry.config.options;
    }

    const opt = optionsSchema?.[focused.name];
    if (opt?.autocomplete) {
      const choices = await opt.autocomplete(interaction, focused.value);
      await interaction.respond(choices).catch(() => null);
    }
  }

  private async routeButton(interaction: ButtonInteraction) {
    const [prefix] = interaction.customId.split(":");
    if (!prefix) return;

    const component = this.components.get(prefix);
    if (!component) return;

    try {
      const args = component.parseArgs(interaction.customId);
      await component.config.run(interaction, args);
    } catch (err) {
      this.logger.error(`error executing button ${prefix}:`, {
        error: err instanceof Error ? err.stack : String(err),
        component: prefix,
        user: interaction.user.id,
      });
    }
  }

  private parseSlashOptions(
    interaction: ChatInputCommandInteraction,
    optionsSchema?: Record<string, Option<any, any>>,
  ): Record<string, any> {
    if (!optionsSchema) return {};
    const parsed: Record<string, any> = {};

    for (const [name, opt] of Object.entries(optionsSchema)) {
      switch (opt.type) {
        case "string":
          parsed[name] = interaction.options.getString(name);
          break;
        case "integer":
          parsed[name] = interaction.options.getInteger(name);
          break;
        case "number":
          parsed[name] = interaction.options.getNumber(name);
          break;
        case "boolean":
          parsed[name] = interaction.options.getBoolean(name);
          break;
        case "user":
          parsed[name] = interaction.options.getUser(name);
          break;
        case "channel":
          parsed[name] = interaction.options.getChannel(name);
          break;
        case "role":
          parsed[name] = interaction.options.getRole(name);
          break;
        case "mentionable":
          parsed[name] = interaction.options.getMentionable(name);
          break;
        case "attachment":
          parsed[name] = interaction.options.getAttachment(name);
          break;
      }
    }
    return parsed;
  }

  async sync({ guildId }: { guildId?: string } = {}) {
    const payloads = Array.from(this.commands.values()).map((cmd) => {
      if (cmd instanceof SubcommandGroupBuilder) {
        const subcommandOptions = Object.values(cmd.subcommands).map((sub) => ({
          type: OPTION_TYPES.subcommand,
          name: sub.name,
          description: sub.config.description,
          options: this.transformOptionsForDiscord(sub.config.options),
        }));

        const groupOptions = Object.values(cmd.groups).map((group) => ({
          type: OPTION_TYPES.subcommandGroup,
          name: group.name,
          description: group.description,
          options: Object.values(group.subcommands).map((sub) => ({
            type: OPTION_TYPES.subcommand,
            name: sub.name,
            description: sub.config.description,
            options: this.transformOptionsForDiscord(sub.config.options),
          })),
        }));

        return {
          name: cmd.name,
          description: cmd.description,
          options: [...subcommandOptions, ...groupOptions],
        };
      } else {
        return {
          name: cmd.name,
          description: cmd.config.description,
          options: this.transformOptionsForDiscord(cmd.config.options),
        };
      }
    });

    if (!this.client.application) {
      throw new Error("client application not ready to sync. ensure you await client.login()");
    }

    if (guildId) {
      await this.client.application.commands.set(payloads, guildId);
      this.logger.info(`synced ${payloads.length} commands to guild ${guildId}.`, {
        guildId,
        commandCount: payloads.length,
      });
    } else {
      await this.client.application.commands.set(payloads);
      this.logger.info(`synced ${payloads.length} global commands.`, {
        commandCount: payloads.length,
      });
    }
  }

  private transformOptionsForDiscord(
    options?: Record<string, Option<any, any>>,
  ): ApplicationCommandNonOptionsData[] {
    if (!options) return [];

    return Object.entries(options).map(([name, opt]) => {
      const payload: any = {
        name,
        description: opt.description,
        type: OPTION_TYPES[opt.type],
        required: opt.required,
      };

      if (opt.autocomplete) {
        payload.autocomplete = true;
      }

      return payload as ApplicationCommandNonOptionsData;
    });
  }
}