import fs from "node:fs";
import path from "node:path";

/**
 * Implementations of OpenClaw memory tools for the contractor bridge.
 *
 * OpenClaw's real memory_search uses vector/semantic search; we approximate
 * with keyword matching across workspace memory files. memory_get is a
 * line-range file read and is implemented exactly.
 *
 * These handlers are registered in globalThis._contractorToolHandlers so the
 * MCP proxy can call them via POST /mcp/execute.
 */

type MemorySearchArgs = {
  query?: string;
  maxResults?: number;
  minScore?: number;
  corpus?: "memory" | "wiki" | "all";
};

type MemoryGetArgs = {
  path?: string;
  from?: number;
  lines?: number;
  corpus?: "memory" | "wiki" | "all";
};

/** Collect all memory files in a workspace. */
function collectMemoryFiles(workspace: string): string[] {
  const files: string[] = [];
  const memoryMd = path.join(workspace, "MEMORY.md");
  if (fs.existsSync(memoryMd)) files.push(memoryMd);

  const memoryDir = path.join(workspace, "memory");
  if (fs.existsSync(memoryDir)) {
    for (const f of fs.readdirSync(memoryDir)) {
      if (f.endsWith(".md")) files.push(path.join(memoryDir, f));
    }
  }
  return files;
}

/** Score a file's relevance to a query by counting keyword occurrences. */
function scoreFile(content: string, query: string): { score: number; snippets: string[] } {
  const words = query.toLowerCase().split(/\s+/).filter(Boolean);
  const lines = content.split("\n");
  const snippets: string[] = [];
  let score = 0;

  for (let i = 0; i < lines.length; i++) {
    const line = lines[i].toLowerCase();
    const matches = words.filter((w) => line.includes(w)).length;
    if (matches > 0) {
      score += matches;
      // Include surrounding context (1 line before/after)
      const start = Math.max(0, i - 1);
      const end = Math.min(lines.length - 1, i + 1);
      const snippet = lines.slice(start, end + 1).join("\n").trim();
      if (snippet && !snippets.includes(snippet)) {
        snippets.push(snippet);
      }
    }
  }
  return { score, snippets };
}

export function makeMemorySearchHandler(workspace: string) {
  return async (args: unknown): Promise<string> => {
    const { query = "", maxResults = 5, corpus = "memory" } = args as MemorySearchArgs;

    if (corpus === "wiki") {
      return JSON.stringify({ disabled: true, reason: "wiki corpus not available in contractor bridge" });
    }

    const files = collectMemoryFiles(workspace);
    if (files.length === 0) {
      return JSON.stringify({
        results: [],
        note: "No memory files found in workspace. Memory is empty.",
      });
    }

    const results: Array<{ file: string; score: number; snippets: string[] }> = [];

    for (const filePath of files) {
      try {
        const content = fs.readFileSync(filePath, "utf8");
        const { score, snippets } = scoreFile(content, query);
        if (score > 0) {
          results.push({
            file: path.relative(workspace, filePath),
            score,
            snippets,
          });
        }
      } catch {
        // skip unreadable files
      }
    }

    results.sort((a, b) => b.score - a.score);
    const top = results.slice(0, maxResults);

    if (top.length === 0) {
      return JSON.stringify({
        results: [],
        note: `No memory matches found for query: "${query}"`,
      });
    }

    return JSON.stringify({ results: top });
  };
}

export function makeMemoryGetHandler(workspace: string) {
  return async (args: unknown): Promise<string> => {
    const { path: filePath = "", from, lines, corpus = "memory" } = args as MemoryGetArgs;

    if (corpus === "wiki") {
      return "[memory_get] wiki corpus not available in contractor bridge";
    }

    if (!filePath) return "[memory_get] path is required";

    // Resolve path relative to workspace (prevent path traversal)
    const resolved = path.resolve(workspace, filePath);
    if (!resolved.startsWith(workspace + path.sep) && resolved !== workspace) {
      return `[memory_get] path outside workspace: ${filePath}`;
    }

    if (!fs.existsSync(resolved)) {
      return `[memory_get] file not found: ${filePath}`;
    }

    try {
      const content = fs.readFileSync(resolved, "utf8");
      const allLines = content.split("\n");

      const startLine = from != null ? Math.max(0, from - 1) : 0; // convert 1-based to 0-based
      const endLine = lines != null ? startLine + lines : allLines.length;

      return allLines.slice(startLine, endLine).join("\n");
    } catch (err) {
      return `[memory_get] error reading file: ${String(err)}`;
    }
  };
}

/**
 * Register memory tool handlers into the shared globalThis tool registry.
 * Called by the bridge server on startup.
 */
export function registerMemoryHandlers(workspace: string): void {
  const _G = globalThis as Record<string, unknown>;
  if (!(_G["_contractorToolHandlers"] instanceof Map)) {
    _G["_contractorToolHandlers"] = new Map<string, (args: unknown) => Promise<string>>();
  }
  const registry = _G["_contractorToolHandlers"] as Map<string, (args: unknown) => Promise<string>>;
  registry.set("memory_search", makeMemorySearchHandler(workspace));
  registry.set("memory_get", makeMemoryGetHandler(workspace));
}