import { Prisma } from "@prisma/client";
import { prisma } from "./db.js";

export const WORKSPACE_SEARCH_LIMIT = 100;

// Treat input as literal Unicode words, never FTS operators/column expressions.
// Prefix matching supports type-ahead, including short terms such as "AI".
export function workspaceSearchExpression(query: string): string | null {
  const words = query.match(/[\p{L}\p{N}\p{M}\p{Co}]+/gu);
  return words?.map((word) => `"${word}"*`).join(" AND ") ?? null;
}

export type WorkspaceSearchHit = {
  type: "chat" | "search";
  id: string;
  searchSnippet: string | null;
};

export function workspaceSearchSQL(expression: string) {
  // Batch excerpts after limiting matches. Unary + prevents SQLite from using
  // the IN clause as repeated rowid lookups (and restarting FTS for every row).
  // FTS still uses MATCH and the rowid bounds; IN filters that single scan.
  return Prisma.sql`
    WITH chat_hits AS (
      SELECT c.id, NULL AS message_rowid
      FROM "ChatSearch" JOIN "Chat" c ON c.rowid = "ChatSearch".rowid
      WHERE "ChatSearch" MATCH ${expression}
      UNION ALL
      SELECT m.chatId AS id, MIN(m.rowid) AS message_rowid
      FROM "MessageSearch" JOIN "Message" m ON m.rowid = "MessageSearch".rowid
      WHERE "MessageSearch" MATCH ${expression}
      GROUP BY m.chatId
    ), matches AS (
      SELECT 'chat' AS type, c.id, c.updatedAt, MIN(h.message_rowid) AS message_rowid,
        NULL AS search_rowid
      FROM chat_hits h JOIN "Chat" c ON c.id = h.id
      GROUP BY c.id
      UNION ALL
      SELECT 'search' AS type, s.id, s.updatedAt, NULL AS message_rowid, s.rowid AS search_rowid
      FROM "SavedSearchSearch" JOIN "Search" s ON s.rowid = "SavedSearchSearch".rowid
      WHERE "SavedSearchSearch" MATCH ${expression}
    ), limited AS MATERIALIZED (
      SELECT * FROM matches ORDER BY updatedAt DESC, type, id LIMIT ${WORKSPACE_SEARCH_LIMIT + 1}
    ), message_excerpts AS MATERIALIZED (
      SELECT rowid, substr(snippet("MessageSearch", 0, '', '', ' … ', 24), 1, 480) AS snippet
      FROM "MessageSearch"
      WHERE "MessageSearch" MATCH ${expression}
        AND rowid >= (SELECT MIN(message_rowid) FROM limited)
        AND rowid <= (SELECT MAX(message_rowid) FROM limited)
        AND +rowid IN (SELECT message_rowid FROM limited)
    ), search_excerpts AS MATERIALIZED (
      SELECT rowid, substr(snippet("SavedSearchSearch", -1, '', '', ' … ', 24), 1, 480) AS snippet
      FROM "SavedSearchSearch"
      WHERE "SavedSearchSearch" MATCH ${expression}
        AND rowid >= (SELECT MIN(search_rowid) FROM limited)
        AND rowid <= (SELECT MAX(search_rowid) FROM limited)
        AND +rowid IN (SELECT search_rowid FROM limited)
    )
    SELECT type, id, COALESCE(m.snippet, s.snippet) AS searchSnippet
    FROM limited
    LEFT JOIN message_excerpts m ON m.rowid = limited.message_rowid
    LEFT JOIN search_excerpts s ON s.rowid = limited.search_rowid
    ORDER BY updatedAt DESC, type, id
  `;
}

export async function searchWorkspace(query: string) {
  const expression = workspaceSearchExpression(query);
  if (!expression) return { hits: [], hasMore: false };
  // Match via the inverted indexes first. Hydrate summaries and generate excerpts
  // only for the bounded result set, never fetch full transcripts into JS.
  const hits = await prisma.$queryRaw<WorkspaceSearchHit[]>(workspaceSearchSQL(expression));
  return { hits: hits.slice(0, WORKSPACE_SEARCH_LIMIT), hasMore: hits.length > WORKSPACE_SEARCH_LIMIT };
}