package models

import (
	"fmt"
	"regexp"
	"strconv"
	"strings"
	"time"
	"unicode"

	"git.golem15.com/golem15/summercms/modules/lagoon"
)

// The query parameter kinds of the D-07 list.
const (
	ParamContent  = "content"
	ParamFilter   = "filter"
	ParamTracking = "tracking"
)

// The address options of D-20b.
const (
	HostKeep  = "keep"
	HostWWW   = "www"
	HostBare  = "bare"
	SlashKeep = "keep"
	SlashAdd  = "add"
	SlashDrop = "remove"
)

// Default templates (D-03).
const (
	DefaultTitleTemplate = "%title% | %site%"
	DefaultHomeTemplate  = "%site%"
)

// The phrase keys of the settings refusals.
const (
	errVerifyFilenameInvalid = "golem15.seo::lang.settings.verify_filename_invalid"
	errVerifyFilenameTaken   = "golem15.seo::lang.settings.verify_filename_taken"
	errTemplateUnknown       = "golem15.seo::lang.settings.template_unknown"
	errDomainInvalid         = "golem15.seo::lang.settings.domain_invalid"
)

// QueryParam is one row of the D-07 query-parameter list: a name (a
// trailing * matches a prefix), its kind, and an optional path pattern the
// row is limited to.
type QueryParam struct {
	Name string `json:"name"`
	Kind string `json:"kind"`
	Path string `json:"path"`
}

// VerifyMeta is one extra verification meta tag (D-05).
type VerifyMeta struct {
	Name    string `json:"name"`
	Content string `json:"content"`
}

// VerifyFile is one verification file served from the site root (D-05).
type VerifyFile struct {
	Filename string `json:"filename"`
	Body     string `json:"body"`
}

// DefaultQueryParams is the seeded D-07 list.
func DefaultQueryParams() []QueryParam {
	return []QueryParam{
		{Name: "page", Kind: ParamContent},
		{Name: "utm_*", Kind: ParamTracking},
		{Name: "fbclid", Kind: ParamTracking},
		{Name: "gclid", Kind: ParamTracking},
		{Name: "msclkid", Kind: ParamTracking},
		{Name: "sort", Kind: ParamFilter},
	}
}

// Settings is the SEO settings singleton (row id 1) on golem15_seo_settings
// (D-03, D-05, D-07, D-20b, D-21, D-23). site_name and default_description
// are translatable; the other locales live with the translate plugin.
type Settings struct {
	ID                 uint                          `gorm:"column:id;primaryKey"`
	SiteName           string                        `gorm:"column:site_name"`
	TwitterSite        string                        `gorm:"column:twitter_site"`
	TitleTemplate      string                        `gorm:"column:title_template"`
	HomeTemplate       string                        `gorm:"column:home_template"`
	DefaultDescription string                        `gorm:"column:default_description"`
	DefaultOGImage     string                        `gorm:"column:default_og_image"`
	QueryParams        lagoon.Jsonable[[]QueryParam] `gorm:"column:query_params"`
	NoindexPaths       string                        `gorm:"column:noindex_paths"`
	SearchPaths        string                        `gorm:"column:search_paths"`
	URLHost            string                        `gorm:"column:url_host"`
	URLSlash           string                        `gorm:"column:url_slash"`
	URLLowercase       bool                          `gorm:"column:url_lowercase"`
	VerifyGoogle       string                        `gorm:"column:verify_google"`
	VerifyBing         string                        `gorm:"column:verify_bing"`
	VerifyYandex       string                        `gorm:"column:verify_yandex"`
	VerifyOther        lagoon.Jsonable[[]VerifyMeta] `gorm:"column:verify_other"`
	VerifyFiles        lagoon.Jsonable[[]VerifyFile] `gorm:"column:verify_files"`
	CSVDelimiter       string                        `gorm:"column:csv_delimiter"`
	// LinksNewTab opens links to other sites in a new tab (Links tab, on
	// by default); NofollowDomains and SponsoredDomains list the domains
	// whose links always get nofollow or sponsored, one per line,
	// subdomains included (D-83).
	LinksNewTab      bool   `gorm:"column:links_new_tab"`
	NofollowDomains  string `gorm:"column:nofollow_domains"`
	SponsoredDomains string `gorm:"column:sponsored_domains"`
	// RoutesReportedAt is the time of the newest route report (D-33),
	// written by the report only.
	RoutesReportedAt *time.Time `gorm:"column:routes_reported_at"`
	CreatedAt        *time.Time `gorm:"column:created_at"`
	UpdatedAt        *time.Time `gorm:"column:updated_at"`
}

func (Settings) TableName() string { return "golem15_seo_settings" }

// MorphName names the settings row for translations.
func (Settings) MorphName() string { return `Golem15\SEO\Models\Settings` }

// Fillable lists the form's columns.
func (Settings) Fillable() []string {
	return []string{
		"site_name", "twitter_site", "title_template", "home_template",
		"default_description", "default_og_image", "query_params",
		"noindex_paths", "search_paths", "url_host", "url_slash",
		"url_lowercase", "verify_google", "verify_bing", "verify_yandex",
		"verify_other", "verify_files", "links_new_tab", "nofollow_domains",
		"sponsored_domains",
	}
}

// Rules is empty: the settings controller checks Problems before a save.
func (Settings) Rules() map[string]string { return map[string]string{} }

// DefaultSettings is what the resolver reads when the row is missing.
func DefaultSettings() Settings {
	return Settings{
		ID:            1,
		TitleTemplate: DefaultTitleTemplate,
		HomeTemplate:  DefaultHomeTemplate,
		QueryParams:   lagoon.Jsonable[[]QueryParam]{Data: DefaultQueryParams(), Valid: true},
		URLHost:       HostKeep,
		URLSlash:      SlashKeep,
		LinksNewTab:   true,
	}
}

// Params returns the query-parameter list.
func (s Settings) Params() []QueryParam { return s.QueryParams.Get() }

// OtherMeta returns the extra verification meta tags.
func (s Settings) OtherMeta() []VerifyMeta { return s.VerifyOther.Get() }

// Files returns the verification files.
func (s Settings) Files() []VerifyFile { return s.VerifyFiles.Get() }

// verifyFilename is the allowed form of a verification file name.
var verifyFilename = regexp.MustCompile(`^[A-Za-z0-9._-]+\.(html|txt|xml)$`)

// placeholderPattern finds %name% placeholders in a template.
var placeholderPattern = regexp.MustCompile(`%[A-Za-z0-9_]*%`)

// KnownPlaceholders are the placeholders a template may use.
var KnownPlaceholders = []string{"%title%", "%description%", "%site%"}

// UnknownPlaceholder returns the first placeholder of tpl that is not
// known, "" when every one is.
func UnknownPlaceholder(tpl string) string {
	for _, found := range placeholderPattern.FindAllString(tpl, -1) {
		known := false
		for _, k := range KnownPlaceholders {
			if found == k {
				known = true
				break
			}
		}
		if !known {
			return found
		}
	}
	return ""
}

// Problem is one field refusal: a phrase key and its :name parameters.
// The admin controllers translate it in the request locale.
type Problem struct {
	Key    string
	Params map[string]string
}

// TemplateProblems refuses a template with an unknown placeholder.
func TemplateProblems(tpl string) []Problem {
	if p := UnknownPlaceholder(tpl); p != "" {
		return []Problem{{Key: errTemplateUnknown, Params: map[string]string{"placeholder": p}}}
	}
	return nil
}

// Problems lists the settings refusals per field: templates with an unknown
// placeholder, and verification file names that are malformed or used
// twice (verify_files.<i>.filename).
func (s Settings) Problems() map[string][]Problem {
	out := map[string][]Problem{}
	for field, tpl := range map[string]string{"title_template": s.TitleTemplate, "home_template": s.HomeTemplate} {
		if p := TemplateProblems(tpl); p != nil {
			out[field] = p
		}
	}
	seen := map[string]bool{}
	for i, f := range s.Files() {
		name := strings.TrimSpace(f.Filename)
		key := fmt.Sprintf("verify_files.%d.filename", i)
		switch {
		case !verifyFilename.MatchString(name):
			out[key] = []Problem{{Key: errVerifyFilenameInvalid}}
		case seen[strings.ToLower(name)]:
			out[key] = []Problem{{Key: errVerifyFilenameTaken}}
		}
		seen[strings.ToLower(name)] = true
	}
	for field, list := range map[string]string{"nofollow_domains": s.NofollowDomains, "sponsored_domains": s.SponsoredDomains} {
		if p := DomainProblems(list); p != nil {
			out[field] = p
		}
	}
	return out
}

// domainLabel is one label of a host name: letters (any script, written
// in lowercase), digits and inner hyphens, at most 63 bytes.
func domainLabel(label string) bool {
	if label == "" || len(label) > 63 || strings.HasPrefix(label, "-") || strings.HasSuffix(label, "-") {
		return false
	}
	for _, r := range label {
		if r != '-' && !unicode.IsDigit(r) && !(unicode.IsLetter(r) && !unicode.IsUpper(r)) {
			return false
		}
	}
	return true
}

// ValidDomain reports whether d is a host name with at least two labels,
// without a scheme, port, path or trailing dot.
func ValidDomain(d string) bool {
	if d == "" || len(d) > 253 {
		return false
	}
	labels := strings.Split(d, ".")
	if len(labels) < 2 {
		return false
	}
	for _, l := range labels {
		if !domainLabel(l) {
			return false
		}
	}
	return true
}

// DomainLines splits a domain list into its trimmed, lowercased,
// non-empty lines, in order and each once.
func DomainLines(list string) []string {
	out := []string{}
	seen := map[string]bool{}
	for _, line := range strings.Split(strings.ReplaceAll(list, "\r\n", "\n"), "\n") {
		d := strings.ToLower(strings.TrimSpace(line))
		if d == "" || seen[d] {
			continue
		}
		seen[d] = true
		out = append(out, d)
	}
	return out
}

// NormalizeDomains rewrites a domain list as DomainLines, one per line.
func NormalizeDomains(list string) string {
	return strings.Join(DomainLines(list), "\n")
}

// DomainProblems refuses the first line of list that is not a domain
// (settings.domain_invalid with its line number and text).
func DomainProblems(list string) []Problem {
	n := 0
	for _, line := range strings.Split(strings.ReplaceAll(list, "\r\n", "\n"), "\n") {
		n++
		d := strings.ToLower(strings.TrimSpace(line))
		if d == "" || ValidDomain(d) {
			continue
		}
		return []Problem{{Key: errDomainInvalid, Params: map[string]string{"line": strconv.Itoa(n), "value": strings.TrimSpace(line)}}}
	}
	return nil
}

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