import type { FastMCP } from 'fastmcp';
import { UserError } from 'fastmcp';
import { z } from 'zod';
import { google } from 'googleapis';
import { getAuthClient } from '../../../clients.js';

export function register(server: FastMCP) {
  server.addTool({
    name: 'getSheetsComment',
    description:
      'Gets a specific comment and its full reply thread from a Google Spreadsheet. Use listSheetsComments first to find the comment ID.',
    parameters: z.strictObject({
      spreadsheetId: z
        .string()
        .describe(
          'The spreadsheet ID — the long string between /d/ and /edit in a Google Sheets URL.'
        ),
      commentId: z.string().describe('The ID of the comment to retrieve.'),
    }),
    execute: async (args, { log }) => {
      log.info(`Getting comment ${args.commentId} from spreadsheet ${args.spreadsheetId}`);

      try {
        const authClient = await getAuthClient();
        const drive = google.drive({ version: 'v3', auth: authClient });
        const response = await drive.comments.get({
          fileId: args.spreadsheetId,
          commentId: args.commentId,
          fields:
            'id,content,anchor,quotedFileContent,author,createdTime,modifiedTime,resolved,replies(id,content,author,createdTime)',
        });

        const comment = response.data;
        const cellInfo = comment.anchor ? parseSheetsAnchor(comment.anchor) : null;

        return JSON.stringify(
          {
            id: comment.id,
            author: comment.author?.displayName || null,
            content: comment.content,
            cell: cellInfo ? rowColToA1(cellInfo.row, cellInfo.col) : null,
            quotedText: comment.quotedFileContent?.value || null,
            resolved: comment.resolved || false,
            createdTime: comment.createdTime,
            modifiedTime: comment.modifiedTime,
            replies: (comment.replies || []).map((r: any) => ({
              id: r.id,
              author: r.author?.displayName || null,
              content: r.content,
              createdTime: r.createdTime,
            })),
          },
          null,
          2
        );
      } catch (error: any) {
        log.error(`Error getting sheets comment: ${error.message || error}`);
        throw new UserError(`Failed to get comment: ${error.message || 'Unknown error'}`);
      }
    },
  });
}

function parseSheetsAnchor(
  anchorStr: string
): { sheetId: number; row: number; col: number } | null {
  try {
    const anchor = JSON.parse(anchorStr);
    const actions = anchor.a;
    if (!actions || !Array.isArray(actions)) return null;
    for (const action of actions) {
      if (action.sht) {
        const sid = action.sht.sid;
        const rng = action.sht.rng;
        if (sid !== undefined && rng) {
          return { sheetId: sid, row: rng.r || 0, col: rng.c || 0 };
        }
      }
    }
    return null;
  } catch {
    return null;
  }
}

function rowColToA1(row: number, col: number): string {
  let colStr = '';
  let c = col;
  do {
    colStr = String.fromCharCode(65 + (c % 26)) + colStr;
    c = Math.floor(c / 26) - 1;
  } while (c >= 0);
  return `${colStr}${row + 1}`;
}