package cabana

import (
	"context"
	"fmt"
	"reflect"

	"git.golem15.com/golem15/summercms/modules/compass"
	"git.golem15.com/golem15/summercms/modules/lagoon"
	"git.golem15.com/golem15/summercms/modules/phrasebook"
	"git.golem15.com/golem15/summercms/modules/seaglass"
)

// passwordFieldType is the write-only secret type on a settings form.
const passwordFieldType = "password"

// SecretFallbacks is implemented by a settings model whose write-only
// password fields fall back to host configuration when the column is empty
// (Phase 18 D-13). The map is field name to compass config key; SUMMER_*
// environment variables map onto those keys as everywhere else. A field
// whose column is empty and whose key resolves to a non-empty value reports
// the env state; the value itself is never read by cabana beyond that check.
type SecretFallbacks interface {
	SecretFallbacks() map[string]string
}

// The states of a write-only settings secret in SettingsMeta.Secrets.
const (
	// SecretStored means the column holds a value.
	SecretStored = "stored"
	// SecretEnv means the column is empty and the model's SecretFallbacks
	// config key resolves to a non-empty value.
	SecretEnv = "env"
	// SecretEmpty means the column is empty and no fallback applies.
	SecretEmpty = "empty"
)

// SettingsMeta is the meta of a settings result: the state of every
// write-only password field (never its value) and the save notices of the
// richeditor fields. The key is omitted when there is nothing to report.
type SettingsMeta struct {
	// Secrets maps each password field to stored, env or empty.
	Secrets map[string]string `json:"secrets,omitempty"`
	// Notices are what the seaglass sanitizer removed from richeditor
	// values on this save.
	Notices []FieldNotice `json:"notices,omitempty"`
}

var encryptedGoType = reflect.TypeOf(lagoon.Encrypted{})

// checkSecretType refuses a password field of a settings form whose model
// column is not a lagoon.Encrypted (or a pointer to one).
func checkSecretType(model any, field FormField) error {
	sf, ok := structFieldByColumn(model, field.Name)
	if !ok {
		return fmt.Errorf("field %s is not a model column", field.Name)
	}
	t := sf.Type
	if t.Kind() == reflect.Pointer {
		t = t.Elem()
	}
	if t != encryptedGoType {
		return fmt.Errorf("field %s: password on a settings form needs a lagoon.Encrypted column, found %s", field.Name, sf.Type)
	}
	return nil
}

// secretStates reports the state of every password field of the setting on
// the loaded model: stored when the column holds a value, env when it is
// empty and the model's fallback key resolves in cfg, else empty. The
// result is nil when the form has no password field.
func secretStates(setting *CompiledSetting, model any, cfg *compass.Config) map[string]string {
	if setting == nil || len(setting.Secrets) == 0 {
		return nil
	}
	var fallbacks map[string]string
	if provider, ok := model.(SecretFallbacks); ok && provider != nil {
		fallbacks = provider.SecretFallbacks()
	}
	states := make(map[string]string, len(setting.Secrets))
	for _, name := range setting.Secrets {
		states[name] = SecretEmpty
		if secretStored(model, name) {
			states[name] = SecretStored
			continue
		}
		if key := fallbacks[name]; key != "" && cfg != nil && cfg.String(key) != "" {
			states[name] = SecretEnv
		}
	}
	return states
}

// secretStored reports whether the model's Encrypted column holds a value.
func secretStored(model any, column string) bool {
	v := reflect.ValueOf(model)
	for v.Kind() == reflect.Pointer {
		if v.IsNil() {
			return false
		}
		v = v.Elem()
	}
	f := fieldByColumn(v, column)
	if !f.IsValid() || !f.CanInterface() {
		return false
	}
	switch e := f.Interface().(type) {
	case lagoon.Encrypted:
		return e.Reveal() != ""
	case *lagoon.Encrypted:
		return e != nil && e.Reveal() != ""
	}
	return false
}

// liftSecretValues applies the write-only semantics to the settings body
// before projection (D-13): an absent key or an empty string keeps the
// stored value, so the key is dropped; JSON null clears it and stays; any
// other string replaces it; a value that is neither is a 422 on the field.
// The body is edited in place and the value is never copied anywhere else.
func liftSecretValues(setting *CompiledSetting, body map[string]any) error {
	for _, name := range setting.Secrets {
		value, present := body[name]
		if !present {
			continue
		}
		switch v := value.(type) {
		case nil:
		case string:
			if v == "" {
				delete(body, name)
			}
		default:
			return &ValidationError{Details: fillTypeDetails(name)}
		}
	}
	return nil
}

// withoutSecrets is the settings data projection without the password
// fields: a secret never leaves the server, in a GET or a PUT answer.
func withoutSecrets(setting *CompiledSetting, data map[string]any) map[string]any {
	if setting == nil || len(setting.Secrets) == 0 {
		return data
	}
	out := make(map[string]any, len(data))
	for key, value := range data {
		out[key] = value
	}
	for _, name := range setting.Secrets {
		delete(out, name)
	}
	return out
}

// checkSettingRichEditors refuses a submitted richeditor value of a settings
// form that is neither a string nor null, before anything is written.
func checkSettingRichEditors(setting *CompiledSetting, body map[string]any) error {
	for _, field := range setting.Form.Fields {
		if field.Type != richEditorType {
			continue
		}
		value, present := body[field.Name]
		if !present {
			continue
		}
		switch value.(type) {
		case nil, string:
		default:
			return &ValidationError{Details: fillTypeDetails(field.Name)}
		}
	}
	return nil
}

// sanitizeSettingRichEditors runs every projected richeditor value of a
// settings form through seaglass, the gate the controller save uses, and
// writes the clean value back; what the policy removed comes back as
// notices on the field.
func sanitizeSettingRichEditors(setting *CompiledSetting, projected map[string]any) []pluginNotice {
	var notices []pluginNotice
	for _, field := range setting.Form.Fields {
		if field.Type != richEditorType {
			continue
		}
		key := field.Name
		for _, w := range setting.Writable {
			if w.Name == field.Name {
				key = w.FillKey
			}
		}
		text, ok := projected[key].(string)
		if !ok {
			continue
		}
		clean, report := seaglass.SanitizeReport(text)
		projected[key] = clean
		for _, notice := range richEditorNotices(report) {
			notices = append(notices, pluginNotice{field: field.Name, notice: notice})
		}
	}
	return notices
}

// settingsMeta builds the result meta, nil when there is nothing to report.
func settingsMeta(ctx context.Context, tr *phrasebook.Translator, secrets map[string]string, notices []pluginNotice) *SettingsMeta {
	localized := localizeNotices(ctx, tr, notices)
	if len(secrets) == 0 && len(localized) == 0 {
		return nil
	}
	return &SettingsMeta{Secrets: secrets, Notices: localized}
}