package sandbox

// forms_module.go
//
// Starlark forms module — validates form data against typed form templates.
// Gated by the forms.validate extension permission.
//
// Starlark API:
//   result = forms.validate(template, data)
//   # result["valid"]  → True/False
//   # result["errors"] → [{"key": "...", "message": "..."}, ...]

import (
	"context"
	"encoding/json"
	"fmt"

	"go.starlark.net/starlark"
	"go.starlark.net/starlarkstruct"

	"armature/forms"
)

// BuildFormsModule creates the "forms" Starlark module.
// Requires the forms.validate permission.
func BuildFormsModule(_ context.Context) *starlarkstruct.Module {
	return MakeModule("forms", starlark.StringDict{
		"validate": starlark.NewBuiltin("forms.validate", formsValidateBuiltin()),
	})
}

func formsValidateBuiltin() func(*starlark.Thread, *starlark.Builtin, starlark.Tuple, []starlark.Tuple) (starlark.Value, error) {
	return func(_ *starlark.Thread, b *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
		var templateVal, dataVal starlark.Value
		if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 2, &templateVal, &dataVal); err != nil {
			return nil, err
		}

		// Convert template dict → Go map → JSON → TypedFormTemplate
		templateDict, ok := templateVal.(*starlark.Dict)
		if !ok {
			return nil, fmt.Errorf("forms.validate: template must be a dict, got %s", templateVal.Type())
		}
		templateMap := DictToMap(templateDict)
		templateJSON, err := json.Marshal(templateMap)
		if err != nil {
			return nil, fmt.Errorf("forms.validate: failed to marshal template: %w", err)
		}

		tpl := forms.ParseTypedFormTemplate(json.RawMessage(templateJSON))
		if tpl == nil {
			return nil, fmt.Errorf("forms.validate: template is invalid or empty")
		}

		// Convert data dict → Go map
		dataDict, ok := dataVal.(*starlark.Dict)
		if !ok {
			return nil, fmt.Errorf("forms.validate: data must be a dict, got %s", dataVal.Type())
		}
		dataMap := DictToMap(dataDict)

		// Coerce to map[string]interface{}
		data := make(map[string]interface{}, len(dataMap))
		for k, v := range dataMap {
			data[k] = v
		}

		// Validate
		errs := forms.ValidateFormData(tpl, data)

		// Build result dict
		errList := make([]starlark.Value, len(errs))
		for i, e := range errs {
			d := starlark.NewDict(2)
			_ = d.SetKey(starlark.String("key"), starlark.String(e.Key))
			_ = d.SetKey(starlark.String("message"), starlark.String(e.Message))
			errList[i] = d
		}

		result := starlark.NewDict(2)
		_ = result.SetKey(starlark.String("valid"), starlark.Bool(len(errs) == 0))
		_ = result.SetKey(starlark.String("errors"), starlark.NewList(errList))

		return result, nil
	}
}