/**
 * write — built-in tool to create/overwrite files (ARCHITECTURE §4.1).
 *
 * Writes `content` to `path` (resolved relative to cwd), creating parent
 * directories as needed. Overwrites existing files. Returns a status message
 * with byte count on success, or an `isError` result on permission/disk failure.
 * Never throws across the seam.
 */
import { Type, type Static } from '@sinclair/typebox';
import { Value } from '@sinclair/typebox/value';
import { resolve, dirname } from 'node:path';
import { mkdir } from 'node:fs/promises';
import type { Tool, ToolContext, ToolResult } from '@/contracts/tool';
import type { RenderDescriptor } from '@/contracts/render-descriptor';

// ── Input schema ──────────────────────────────────────────────────────────────

export const WriteInputSchema = Type.Object({
  path: Type.String({ description: 'File path, resolved relative to cwd' }),
  content: Type.String({ description: 'Content to write to the file' }),
});

export type WriteInput = Static<typeof WriteInputSchema>;

// ── Tool definition ───────────────────────────────────────────────────────────

export const writeTool: Tool<typeof WriteInputSchema> = {
  name: 'write',
  description:
    'Write content to a file. Creates parent directories automatically. Overwrites if the file exists.',
  inputSchema: WriteInputSchema,
  isReadOnly: false,

  async execute(input: WriteInput, ctx: ToolContext): Promise<ToolResult> {
    // Validate input against schema
    if (!Value.Check(WriteInputSchema, input)) {
      return {
        content: { kind: 'error', message: `Invalid input for write tool: ${JSON.stringify(input)}` },
        isError: true,
      };
    }

    const filePath = resolve(ctx.cwd, input.path);

    try {
      // Ensure parent directory exists
      await mkdir(dirname(filePath), { recursive: true });

      await Bun.write(filePath, input.content);

      const byteLength = new TextEncoder().encode(input.content).length;
      return {
        content: { kind: 'text', text: `wrote ${byteLength} bytes to ${input.path}` },
        isError: false,
        // duoh76.6: absolute path for the FileMutationNotifier. The error paths below
        // don't set this (no mutation happened).
        mutatedFiles: [filePath],
      };
    } catch (err) {
      const message = err instanceof Error ? err.message : String(err);
      return {
        content: { kind: 'error', message: `Failed to write ${filePath}: ${message}` },
        isError: true,
      };
    }
  },

  onStart(input: WriteInput): RenderDescriptor {
    return { kind: 'status', label: `writing ${input.path}`, tone: 'info' };
  },

  onResult(input: WriteInput, result: ToolResult): RenderDescriptor {
    if (result.isError) {
      const content = result.content as { kind: 'error'; message: string };
      return { kind: 'status', label: `error writing ${input.path}: ${content.message}`, tone: 'error' };
    }
    return { kind: 'status', label: `wrote ${input.path}`, tone: 'info' };
  },
};