import * as os from "os";
import { Message, TextChannel } from "discord.js";
import { DisclawDatabase } from "./db/database";
import { DisclawConfig } from "./config/loader";
import { runAgent } from "./agent/runner";
import { sanitizeForDiscord } from "./runtime/sanitize";

const DISCORD_MAX_LENGTH = 2000;

/**
 * Splits a message at line breaks so each chunk stays under the Discord
 * character limit. If a single line exceeds the limit, it is split at
 * the character boundary as a last resort.
 */
function splitMessage(text: string): string[] {
  if (text.length <= DISCORD_MAX_LENGTH) {
    return [text];
  }

  const chunks: string[] = [];
  const lines = text.split("\n");
  let current = "";

  for (const line of lines) {
    // If adding this line would exceed the limit, flush current chunk
    if (current.length + line.length + 1 > DISCORD_MAX_LENGTH) {
      if (current.length > 0) {
        chunks.push(current);
        current = "";
      }

      // Handle lines that are themselves too long
      if (line.length > DISCORD_MAX_LENGTH) {
        let remaining = line;
        while (remaining.length > DISCORD_MAX_LENGTH) {
          chunks.push(remaining.slice(0, DISCORD_MAX_LENGTH));
          remaining = remaining.slice(DISCORD_MAX_LENGTH);
        }
        if (remaining.length > 0) {
          current = remaining;
        }
        continue;
      }
    }

    current += (current.length > 0 ? "\n" : "") + line;
  }

  if (current.length > 0) {
    chunks.push(current);
  }

  return chunks;
}

/**
 * Routes a Discord message to the correct agent based on channel_id.
 * Returns true if the message was handled, false if the channel is not
 * mapped to any agent.
 */
export async function routeMessage(
  message: Message,
  db: DisclawDatabase,
  config: DisclawConfig,
  managementChannelId: string | null
): Promise<boolean> {
  const channelId = message.channelId;

  // Ignore messages in the management channel (commands only)
  if (channelId === managementChannelId) {
    return false;
  }

  // Look up workspace for this channel
  const workspace = db.getWorkspaceByChannelId(channelId);
  if (!workspace) {
    return false;
  }

  const channel = message.channel as TextChannel;

  // Show typing indicator while the agent works
  const typingInterval = setInterval(() => {
    channel.sendTyping().catch(() => {});
  }, 5000);
  // Send immediately as well
  await channel.sendTyping().catch(() => {});

  try {
    // Load recent conversation history for context
    const history = db.getConversationHistory(workspace.id, 30);

    // Run the agent
    const response = await runAgent({
      workspacePath: workspace.workspace_path,
      channelName: channel.name,
      userMessage: message.content,
      conversationHistory: history,
    });

    // Store user message
    db.addConversation(
      workspace.id,
      message.id,
      "user",
      message.content,
      message.author.username
    );

    // Split and send response
    const chunks = splitMessage(response);
    let firstMsgId: string | null = null;

    for (const chunk of chunks) {
      const sent = await channel.send(sanitizeForDiscord(chunk, { home: os.homedir() }));
      if (!firstMsgId) {
        firstMsgId = sent.id;
      }
    }

    // Store assistant response (use first message id for dedup)
    if (firstMsgId) {
      db.addConversation(
        workspace.id,
        firstMsgId,
        "assistant",
        response,
        null
      );
    }
  } catch (error) {
    const msg = error instanceof Error ? error.message : "Unbekannter Fehler";
    const safeMsg = sanitizeForDiscord(`Fehler bei der Verarbeitung: ${msg}`, { home: os.homedir() });
    await channel.send(safeMsg).catch(() => {});
  } finally {
    clearInterval(typingInterval);
  }

  return true;
}