package models

import (
	"net/url"
	"strings"
	"unicode"
	"unicode/utf8"

	"git.golem15.com/golem15/summercms/modules/cabana"
	"gorm.io/gorm"
)

// errFrontendURL is the phrase key of the frontend_url refusal.
const errFrontendURL = "golem15.sitemap::lang.errors.frontend_url"

// The settings keys of the five priority tiers, in the order PHP checked
// them. A tier rule names one of them.
const (
	PriorityHomepage   = "priority_homepage"
	PriorityServices   = "priority_services"
	PriorityBlog       = "priority_blog"
	PriorityCategories = "priority_categories"
	PriorityLegal      = "priority_legal"
)

// PriorityDefaults are the PHP defaults of the priority settings.
var PriorityDefaults = map[string]string{
	PriorityHomepage:   "1.0",
	PriorityServices:   "0.8",
	PriorityBlog:       "0.6",
	PriorityCategories: "0.4",
	PriorityLegal:      "0.2",
}

// Settings is the sitemap settings singleton (row id 1) on
// golem15_sitemap_settings, the PHP Golem15\Sitemap\Models\Settings that
// WinterCMS kept in system_settings under golem15_sitemap_settings.
// FrontendURL replaces the backend URL in the generated XML;
// FrontendDefaultLocale is the locale whose URLs carry no prefix;
// UpdatesManifestPath names a JSON file of URL path to last-modified date;
// EnablePriorityTiers turns the tier priorities on, and the priority fields
// hold each tier's value as text. A null priority reads as its PHP default.
// The PHP settings form validated nothing; the port checks FrontendURL in
// BeforeValidate.
type Settings struct {
	ID                    uint    `gorm:"column:id;primaryKey"`
	FrontendURL           *string `gorm:"column:frontend_url"`
	FrontendDefaultLocale *string `gorm:"column:frontend_default_locale"`
	UpdatesManifestPath   *string `gorm:"column:updates_manifest_path"`
	EnablePriorityTiers   bool    `gorm:"column:enable_priority_tiers"`
	PriorityHomepage      *string `gorm:"column:priority_homepage"`
	PriorityServices      *string `gorm:"column:priority_services"`
	PriorityBlog          *string `gorm:"column:priority_blog"`
	PriorityCategories    *string `gorm:"column:priority_categories"`
	PriorityLegal         *string `gorm:"column:priority_legal"`
}

func (Settings) TableName() string { return "golem15_sitemap_settings" }

// Fillable lists only the settings columns.
func (Settings) Fillable() []string {
	return []string{
		"frontend_url", "frontend_default_locale", "updates_manifest_path",
		"enable_priority_tiers", PriorityHomepage, PriorityServices,
		PriorityBlog, PriorityCategories, PriorityLegal,
	}
}

// Rules is empty: the PHP settings form validated nothing. The one check of
// the port, on frontend_url, is in BeforeValidate.
func (Settings) Rules() map[string]string { return map[string]string{} }

// BeforeValidate is the lagoon.HasBeforeValidate hook cabana calls on a
// settings save, after the fill and before the row is written: a
// frontend_url that AllowedFrontendURL refuses is a validation error on
// frontend_url, so the save answers 422 and the row is left as it was.
func (s Settings) BeforeValidate(*gorm.DB) error {
	if AllowedFrontendURL(Text(s.FrontendURL)) {
		return nil
	}
	return &cabana.ValidationError{Details: map[string]any{"frontend_url": []string{errFrontendURL}}}
}

// AllowedFrontendURL reports whether u may be the frontend_url setting: the
// empty string, or an absolute http or https URL with a host and without
// whitespace, control characters, a double quote, <, > or &. The PHP plugin
// stored any text. The value is written into every loc, every hreflang link
// and the stylesheet instruction of the sitemap, and sitemap.xsl renders
// each loc as a link on the public origin, so a value outside this form
// (a javascript: URL, or text that closes the attribute it is written into)
// would reach the readers of /sitemap.xml (T-17-15).
func AllowedFrontendURL(u string) bool {
	if u == "" {
		return true
	}
	if !utf8.ValidString(u) {
		return false
	}
	if strings.ContainsFunc(u, func(r rune) bool {
		return unicode.IsControl(r) || unicode.IsSpace(r) || r == '"' || r == '<' || r == '>' || r == '&'
	}) {
		return false
	}
	parsed, err := url.Parse(u)
	if err != nil {
		return false
	}
	if parsed.Scheme != "http" && parsed.Scheme != "https" {
		return false
	}
	return parsed.Opaque == "" && parsed.Hostname() != ""
}

// DefaultSettings is the settings PHP read when nothing was saved: tiers on
// with the default priorities.
func DefaultSettings() Settings {
	return Settings{ID: 1, EnablePriorityTiers: true}
}

// Priority returns the value of a priority setting: the stored text, or the
// PHP default when it is null.
func (s Settings) Priority(key string) string {
	var p *string
	switch key {
	case PriorityHomepage:
		p = s.PriorityHomepage
	case PriorityServices:
		p = s.PriorityServices
	case PriorityBlog:
		p = s.PriorityBlog
	case PriorityCategories:
		p = s.PriorityCategories
	case PriorityLegal:
		p = s.PriorityLegal
	}
	if p == nil {
		return PriorityDefaults[key]
	}
	return *p
}

func init() {
	Register(Settings{})
}