package builtin

import (
	"context"
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"

	"nub/internal/tool"
)

type WriteTool struct{}

func (WriteTool) Name() string { return "write" }
func (WriteTool) Description() string {
	return "Schreibt eine Datei vollständig (legt Parent-Dirs an)."
}

func (WriteTool) Schema() json.RawMessage {
	return json.RawMessage(`{
		"type": "object",
		"properties": {
			"path":    {"type": "string"},
			"content": {"type": "string"}
		},
		"required": ["path", "content"]
	}`)
}

type writeInput struct {
	Path    string `json:"path"`
	Content string `json:"content"`
}

func (WriteTool) Run(ctx context.Context, input json.RawMessage, env tool.Env) (tool.Result, error) {
	var in writeInput
	if err := json.Unmarshal(input, &in); err != nil {
		return tool.Result{ForModel: "invalid input: " + err.Error(), IsError: true}, nil
	}
	path, err := resolvePath(env.RepoRoot, env.Cwd, in.Path)
	if err != nil {
		return tool.Result{ForModel: err.Error(), IsError: true}, nil
	}

	old, _ := os.ReadFile(path) // fehlt die Datei, ist old leer -> reiner Add-Diff

	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return tool.Result{ForModel: fmt.Sprintf("write %s: %v", in.Path, err), IsError: true}, nil
	}
	if err := os.WriteFile(path, []byte(in.Content), 0o644); err != nil {
		return tool.Result{ForModel: fmt.Sprintf("write %s: %v", in.Path, err), IsError: true}, nil
	}

	return tool.Result{
		ForModel: fmt.Sprintf("wrote %s (%d bytes)", in.Path, len(in.Content)),
		ForUI:    DiffResult{Path: in.Path, Lines: lineDiff(string(old), in.Content)},
	}, nil
}