package handler

import (
	"encoding/json"

	"github.com/gofiber/fiber/v3"
)

// defaultSettings returns the default settings map.
func defaultSettings() map[string]any {
	return map[string]any{
		"defaultUserAgent":                  "clash.meta/v1.19.24",
		"defaultFlowUserAgent":              "clash.meta/v1.19.24",
		"defaultTimeout":                    "30000",
		"backendRequestConcurrency":         "3",
		"backendRequestConcurrencyWaitTime": "100",
		"remoteCacheTtl":                    "300",
		"remoteCacheStaleOnError":           true,
		"nodeInfoApiUrl":                    "https://ipwho.is/{ip}",
		"theme": map[string]any{
			"auto":  true,
			"name":  "light",
			"dark":  "dark",
			"light": "light",
		},
		"appearanceSetting": map[string]any{
			"isSimpleMode":                       true,
			"isLeftRight":                        false,
			"isDefaultIcon":                      false,
			"isIconColor":                        false,
			"isShowIcon":                         true,
			"isSimpleShowRemark":                 false,
			"isEditorCommon":                     false,
			"manualSubscriptionsDisplayMode":     "collapsed",
			"editorGroupingMode":                 "always",
			"isSimpleReicon":                     false,
			"isSubItemMenuFold":                  true,
			"showFloatingRefreshButton":          false,
			"showFloatingAddButton":              false,
			"createItemPosition":                 "bottom",
			"displayPreviewInWebPage":            true,
			"subProgressStyle":                   "hidden",
			"listPageViewMode":                   "single-column",
			"listPageViewModeInWideScreenNarrowMode": "single-column",
			"useNarrowModeOnWideScreen":          false,
		},
		"appName": "Sub-Store",
	}
}

// mergeSettings merges default + stored settings.
// Per review-resolution #4: top-level keys from stored override default;
// theme and appearanceSetting are shallow-merged (stored child keys override default child keys).
func mergeSettings(base, stored map[string]any) map[string]any {
	result := make(map[string]any, len(base))
	for k, v := range base {
		result[k] = v
	}
	for k, v := range stored {
		if v != nil {
			result[k] = v
		}
	}
	// Shallow merge for theme and appearanceSetting
	result["theme"] = shallowMergeObject(base["theme"], stored["theme"])
	result["appearanceSetting"] = shallowMergeObject(base["appearanceSetting"], stored["appearanceSetting"])
	return result
}

func shallowMergeObject(base, overlay any) map[string]any {
	result := map[string]any{}
	if b, ok := base.(map[string]any); ok {
		for k, v := range b {
			result[k] = v
		}
	}
	if o, ok := overlay.(map[string]any); ok {
		for k, v := range o {
			if v != nil {
				result[k] = v
			}
		}
	}
	return result
}

// HandleGetSettings returns merged settings.
func (d *Deps) HandleGetSettings(c fiber.Ctx) error {
	stored, err := d.SettingsRepo.Get()
	if err != nil {
		return failed(c, "Failed to read settings", 500)
	}
	return success(c, mergeSettings(defaultSettings(), stored))
}

// HandleUpdateSettings patches settings.
func (d *Deps) HandleUpdateSettings(c fiber.Ctx) error {
	var input map[string]any
	if err := json.Unmarshal(c.Body(), &input); err != nil {
		input = map[string]any{}
	}
	merged, err := d.SettingsRepo.Update(input)
	if err != nil {
		return failed(c, "Failed to update settings", 500)
	}
	return success(c, mergeSettings(defaultSettings(), merged))
}

// HandleExportStorage exports all data.
// Per review-resolution #31: exclude built-in templates.
func (d *Deps) HandleExportStorage(c fiber.Ctx) error {
	sources, _ := d.SourceRepo.List()
	collections, _ := d.CollectionRepo.List()
	templates, _ := d.TemplateRepo.List()
	settings, _ := d.SettingsRepo.Get()

	// Filter out built-in templates
	exportedTemplates := make([]any, 0, len(templates))
	builtinIDs := getBuiltinTemplateIDs()
	for _, t := range templates {
		if !builtinIDs[t.ID] {
			exportedTemplates = append(exportedTemplates, t)
		}
	}

	// Actually filter properly — already done above

	payload := fiber.Map{
		"version":     1,
		"exportedAt":  "now",
		"settings":    settings,
		"sources":     sources,
		"collections": collections,
		"templates":   exportedTemplates,
	}

	c.Set("Content-Type", "application/json; charset=utf-8")
	c.Set("Content-Disposition", `attachment; filename="sub-store-backup.json"`)
	return c.JSON(payload)
}

// HandleImportStorage imports data.
// Per review-resolution #30: import order = settings → sources → templates → collections.
func (d *Deps) HandleImportStorage(c fiber.Ctx) error {
	input, err := parseJsonOrText(c)
	if err != nil {
		return failed(c, "Invalid import payload", 400)
	}

	// Import settings first
	if settings, ok := input["settings"].(map[string]any); ok {
		d.SettingsRepo.Update(settings)
	}

	// Import sources
	if sources, ok := input["sources"].([]any); ok {
		for _, s := range sources {
			if record, ok := s.(map[string]any); ok {
				d.SourceRepo.Upsert(mapToSourceRecord(record))
			}
		}
	}

	// Import templates (before collections, since collections reference templates)
	builtinIDs := getBuiltinTemplateIDs()
	if templates, ok := input["templates"].([]any); ok {
		for _, t := range templates {
			if record, ok := t.(map[string]any); ok {
				id := getStringValue(record["id"])
				if id != "" && !builtinIDs[id] {
					d.TemplateRepo.Upsert(mapToTemplateRecord(record))
				}
			}
		}
	}

	// Import collections last
	if collections, ok := input["collections"].([]any); ok {
		for _, col := range collections {
			if record, ok := col.(map[string]any); ok {
				d.CollectionRepo.Upsert(mapToCollectionRecord(record))
			}
		}
	}

	return success(c, fiber.Map{"restored": true})
}

// parseJsonOrText parses body as JSON, or wraps text as {content: text}.
// Per review-resolution #9: JSON first, plain text fallback.
func parseJsonOrText(c fiber.Ctx) (map[string]any, error) {
	body := c.Body()
	var result map[string]any
	if err := json.Unmarshal(body, &result); err == nil {
		return result, nil
	}
	// Try as string
	text := string(body)
	if text == "" {
		return map[string]any{}, nil
	}
	return map[string]any{"content": text}, nil
}