import { Effect } from "effect";
import type { Executor, ToolMetadata, Source } from "@executor/sdk";

/**
 * Builds a tool description dynamically.
 *
 * Structure:
 *   1. Workflow (top — critical, least likely to be truncated)
 *   2. Available namespaces (bottom)
 */
export const buildExecuteDescription = (executor: Executor): Effect.Effect<string> =>
  Effect.gen(function* () {
    const sources: readonly Source[] = yield* executor.sources.list();
    const tools: readonly ToolMetadata[] = yield* executor.tools.list();

    const namespaces = new Set<string>();
    for (const tool of tools) namespaces.add(tool.sourceId);

    return formatDescription([...namespaces], sources);
  });

const formatDescription = (namespaces: readonly string[], sources: readonly Source[]): string => {
  const lines: string[] = [
    "Execute TypeScript in a sandboxed runtime with access to configured API tools.",
    "",
    "## Workflow",
    "",
    '1. `const matches = await tools.search({ query: "<intent + key nouns>", limit: 12 });`',
    '2. `const path = matches[0]?.path; if (!path) return "No matching tools found.";`',
    "3. `const details = await tools.describe.tool({ path });`",
    "4. Use `details.inputTypeScript` / `details.outputTypeScript` and `details.typeScriptDefinitions` for compact shapes.",
    "5. Use `tools.executor.sources.list()` when you need configured source inventory.",
    "6. Call the tool: `const result = await tools.<path>(input);`",
    "",
    "## Rules",
    "",
    "- `tools.search()` returns ranked matches, best-first. Use short intent phrases like `github issues`, `repo details`, or `create calendar event`.",
    '- When you already know the namespace, narrow with `tools.search({ namespace: "github", query: "issues" })`.',
    "- Use `tools.executor.sources.list()` to inspect configured sources and their tool counts. Returns `[{ id, toolCount, ... }]`.",
    "- Always use the namespace prefix when calling tools: `tools.<namespace>.<tool>(args)`. Example: `tools.home_assistant_rest_api.states.getState(...)` — not `tools.states.getState(...)`.",
    "- The `tools` object is a lazy proxy — `Object.keys(tools)` won't work. Use `tools.search()` or `tools.executor.sources.list()` instead.",
    '- Pass an object to system tools, e.g. `tools.search({ query: "..." })`, `tools.executor.sources.list()`, and `tools.describe.tool({ path })`.',
    "- `tools.describe.tool()` returns compact TypeScript shapes. Use `inputTypeScript`, `outputTypeScript`, and `typeScriptDefinitions`.",
    "- For tools that return large collections (e.g. `getStates`, `getAll`), filter results in code rather than calling per-item tools.",
    "- Do not use `fetch` — all API calls go through `tools.*`.",
    "- If execution pauses for interaction, resume it with the returned `resumePayload`.",
  ];

  if (namespaces.length > 0) {
    lines.push("");
    lines.push("## Available namespaces");
    lines.push("");
    const sorted = [...namespaces].sort();
    for (const ns of sorted) {
      const source = sources.find((s) => s.id === ns);
      const label = source?.name ?? ns;
      lines.push(`- \`${ns}\`${label !== ns ? ` — ${label}` : ""}`);
    }
  }

  return lines.join("\n");
};