import { readFile, readdir, stat } from 'node:fs/promises';
import { resolve, basename, relative } from 'node:path';
import { z } from 'zod';
import { pathGuard, PathScopeError } from './path_guard.js';
import { grep as fileOpsGrep, findFiles as fileOpsFindFiles } from './file_ops.js';

const MAX_FILE_BYTES = 5 * 1024 * 1024;
const DEFAULT_VIEW_LINES = 200;
const MAX_GREP_RESULTS = 200;
const DEFAULT_GREP_RESULTS = 100;
const MAX_FIND_RESULTS = 200;
const DEFAULT_FIND_RESULTS = 100;
const MAX_DIR_ENTRIES = 500;

export interface ToolJsonSchema {
  type: 'function';
  function: {
    name: string;
    description: string;
    parameters: Record<string, unknown>;
  };
}

export interface ToolDef<TInput> {
  name: string;
  description: string;
  inputSchema: z.ZodType<TInput>;
  jsonSchema: ToolJsonSchema;
  execute(input: TInput, projectRoot: string): Promise<unknown>;
}

const ViewFileInput = z.object({
  path: z.string().min(1),
  start_line: z.number().int().positive().optional(),
  end_line: z.number().int().positive().optional(),
});
type ViewFileInputT = z.infer<typeof ViewFileInput>;

export const viewFile: ToolDef<ViewFileInputT> = {
  name: 'view_file',
  description:
    "Read a file under the project. Returns first 200 lines by default, or a slice via start_line/end_line (1-indexed, inclusive). Files larger than 5MB are refused. Output is truncated if longer than the slice; the response indicates truncation.",
  inputSchema: ViewFileInput,
  jsonSchema: {
    type: 'function',
    function: {
      name: 'view_file',
      description:
        "Read a file under the project. Returns first 200 lines by default, or a slice via start_line/end_line (1-indexed, inclusive). Files larger than 5MB are refused.",
      parameters: {
        type: 'object',
        properties: {
          path: { type: 'string', description: 'absolute or project-relative path' },
          start_line: { type: 'integer', description: 'first line (1-indexed)' },
          end_line: { type: 'integer', description: 'last line (1-indexed, inclusive)' },
        },
        required: ['path'],
        additionalProperties: false,
      },
    },
  },
  async execute(input, projectRoot) {
    const real = await pathGuard(projectRoot, input.path);
    const s = await stat(real);
    if (!s.isFile()) {
      throw new PathScopeError(`not a file: ${input.path}`);
    }
    if (s.size > MAX_FILE_BYTES) {
      throw new Error(`file too large (${s.size} bytes, max ${MAX_FILE_BYTES})`);
    }
    const raw = await readFile(real, 'utf8');
    const lines = raw.split('\n');
    const total = lines.length;
    let start = input.start_line ?? 1;
    let end = input.end_line ?? Math.min(total, start + DEFAULT_VIEW_LINES - 1);
    if (input.start_line == null && input.end_line == null) {
      end = Math.min(total, DEFAULT_VIEW_LINES);
    }
    if (start < 1) start = 1;
    if (end > total) end = total;
    if (end < start) end = start;
    const slice = lines.slice(start - 1, end);
    const content = slice.join('\n');
    const truncated = total > end || start > 1;
    return {
      path: relative(projectRoot, real) || basename(real),
      content,
      total_lines: total,
      returned_lines: [start, end],
      truncated,
    };
  },
};

const ListDirInput = z.object({
  path: z.string().min(1),
  show_hidden: z.boolean().optional(),
});
type ListDirInputT = z.infer<typeof ListDirInput>;

export const listDir: ToolDef<ListDirInputT> = {
  name: 'list_dir',
  description: 'List entries in a directory (up to 500). Hidden files excluded unless show_hidden=true.',
  inputSchema: ListDirInput,
  jsonSchema: {
    type: 'function',
    function: {
      name: 'list_dir',
      description:
        'List entries in a directory (up to 500). Hidden files (dot-prefixed) excluded unless show_hidden=true.',
      parameters: {
        type: 'object',
        properties: {
          path: { type: 'string' },
          show_hidden: { type: 'boolean' },
        },
        required: ['path'],
        additionalProperties: false,
      },
    },
  },
  async execute(input, projectRoot) {
    const real = await pathGuard(projectRoot, input.path);
    const s = await stat(real);
    if (!s.isDirectory()) {
      throw new PathScopeError(`not a directory: ${input.path}`);
    }
    const entries = await readdir(real, { withFileTypes: true });
    const filtered = input.show_hidden
      ? entries
      : entries.filter((e) => !e.name.startsWith('.'));
    const total = filtered.length;
    const slice = filtered.slice(0, MAX_DIR_ENTRIES);
    const out = await Promise.all(
      slice.map(async (e) => {
        const child = resolve(real, e.name);
        let size: number | undefined;
        if (e.isFile()) {
          try {
            const cs = await stat(child);
            size = cs.size;
          } catch {
            /* ignore */
          }
        }
        return {
          name: e.name,
          type: e.isDirectory() ? ('dir' as const) : ('file' as const),
          ...(size != null ? { size } : {}),
        };
      })
    );
    return {
      path: relative(projectRoot, real) || '.',
      entries: out,
      total,
      truncated: total > MAX_DIR_ENTRIES,
    };
  },
};

const GrepInput = z.object({
  pattern: z.string().min(1),
  path: z.string().optional(),
  case_sensitive: z.boolean().optional(),
  max_results: z.number().int().positive().optional(),
  hidden: z.boolean().optional(),
});
type GrepInputT = z.infer<typeof GrepInput>;

export const grep: ToolDef<GrepInputT> = {
  name: 'grep',
  description:
    'Search file contents with ripgrep. Default path is project root. Max 100 results (200 cap).',
  inputSchema: GrepInput,
  jsonSchema: {
    type: 'function',
    function: {
      name: 'grep',
      description:
        'Search file contents with ripgrep. Returns up to 100 matches (cap 200). Set hidden=true to include dot-prefixed files.',
      parameters: {
        type: 'object',
        properties: {
          pattern: { type: 'string' },
          path: { type: 'string' },
          case_sensitive: { type: 'boolean' },
          max_results: { type: 'integer' },
          hidden: { type: 'boolean' },
        },
        required: ['pattern'],
        additionalProperties: false,
      },
    },
  },
  async execute(input, projectRoot) {
    const limit = Math.min(
      Math.max(input.max_results ?? DEFAULT_GREP_RESULTS, 1),
      MAX_GREP_RESULTS
    );
    // Delegate to file_ops.grep; reshape match objects to preserve LLM output format
    // (file_ops uses {path, line, text}; tool output uses {path, line, content})
    const result = await fileOpsGrep(projectRoot, input.pattern, {
      path: input.path,
      max_matches: limit,
      case_sensitive: input.case_sensitive,
      hidden: input.hidden,
    });
    return {
      matches: result.matches.map((m) => ({
        path: m.path,
        line: m.line,
        content: m.text,
      })),
      total: result.matches.length,
      truncated: result.truncated,
    };
  },
};

const FindFilesInput = z.object({
  pattern: z.string().min(1),
  path: z.string().optional(),
  max_results: z.number().int().positive().optional(),
});
type FindFilesInputT = z.infer<typeof FindFilesInput>;

export const findFiles: ToolDef<FindFilesInputT> = {
  name: 'find_files',
  description: 'Glob for filenames. Default path is project root. Max 100 results (200 cap).',
  inputSchema: FindFilesInput,
  jsonSchema: {
    type: 'function',
    function: {
      name: 'find_files',
      description:
        'Glob for filenames under a directory. Default path is project root. Max 100 results (cap 200). Pattern uses standard glob (e.g. "**/*.ts").',
      parameters: {
        type: 'object',
        properties: {
          pattern: { type: 'string' },
          path: { type: 'string' },
          max_results: { type: 'integer' },
        },
        required: ['pattern'],
        additionalProperties: false,
      },
    },
  },
  async execute(input, projectRoot) {
    const limit = Math.min(
      Math.max(input.max_results ?? DEFAULT_FIND_RESULTS, 1),
      MAX_FIND_RESULTS
    );
    // Delegate to file_ops.findFiles; reshape { files, total, truncated } to
    // preserve the LLM-visible output format { paths, total, truncated }
    const result = await fileOpsFindFiles(projectRoot, input.pattern, {
      path: input.path,
      max_results: limit,
    });
    return {
      paths: result.files,
      total: result.total,
      truncated: result.truncated,
    };
  },
};

export const ALL_TOOLS: ReadonlyArray<ToolDef<unknown>> = [
  viewFile as ToolDef<unknown>,
  listDir as ToolDef<unknown>,
  grep as ToolDef<unknown>,
  findFiles as ToolDef<unknown>,
];

export const TOOLS_BY_NAME: Record<string, ToolDef<unknown>> = Object.fromEntries(
  ALL_TOOLS.map((t) => [t.name, t])
);

export function toolJsonSchemas(): ToolJsonSchema[] {
  return ALL_TOOLS.map((t) => t.jsonSchema);
}