package models

import (
	"context"
	"crypto/rand"
	"errors"
	"math/big"
	"strconv"
	"strings"
	"time"

	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

// SettingsID is the primary key of the one settings row.
const SettingsID = 1

// SettingsCode is the WinterCMS settings code of the plugin
// (system_settings.item), which feedback:import-settings reads.
const SettingsCode = "golem15_feedback_settings"

// Settings is the golem15_feedback_settings singleton (id 1), the typed Go
// form of the WinterCMS SettingsModel stored under SettingsCode. Defaults
// are Settings::initSettingsData; WidgetKey is generated once, when the row
// is first created (wk_ plus 32 random letters and digits).
type Settings struct {
	ID                    uint      `gorm:"column:id;primaryKey"`
	Enabled               bool      `gorm:"column:enabled"`
	WidgetKey             string    `gorm:"column:widget_key"`
	AllowHide             bool      `gorm:"column:allow_hide"`
	Position              *string   `gorm:"column:position"`
	AllowedOrigins        *string   `gorm:"column:allowed_origins"`
	ColorPrimary          *string   `gorm:"column:color_primary"`
	ColorAccent           *string   `gorm:"column:color_accent"`
	LabelTitlePL          *string   `gorm:"column:label_title_pl"`
	LabelTitleEN          *string   `gorm:"column:label_title_en"`
	LabelPlaceholderPL    *string   `gorm:"column:label_placeholder_pl"`
	LabelPlaceholderEN    *string   `gorm:"column:label_placeholder_en"`
	LabelSuccessPL        *string   `gorm:"column:label_success_pl"`
	LabelSuccessEN        *string   `gorm:"column:label_success_en"`
	G15OfficeTaskStatus   *string   `gorm:"column:g15office_task_status"`
	G15OfficeTaskPriority *string   `gorm:"column:g15office_task_priority"`
	CreatedAt             time.Time `gorm:"column:created_at"`
	UpdatedAt             time.Time `gorm:"column:updated_at"`
}

// TableName is golem15_feedback_settings.
func (Settings) TableName() string { return "golem15_feedback_settings" }

// Fillable is every column the settings form writes.
func (Settings) Fillable() []string {
	return []string{
		"enabled", "widget_key", "allow_hide", "position", "allowed_origins",
		"color_primary", "color_accent",
		"label_title_pl", "label_title_en", "label_placeholder_pl", "label_placeholder_en",
		"label_success_pl", "label_success_en",
		"g15office_task_status", "g15office_task_priority",
	}
}

// Rules are Settings::$rules: every one nullable, the enums checked with in.
func (Settings) Rules() map[string]string {
	return map[string]string{
		"enabled":                 "nullable|boolean",
		"allow_hide":              "nullable|boolean",
		"allowed_origins":         "nullable|string",
		"color_primary":           "nullable|string|max:32",
		"color_accent":            "nullable|string|max:32",
		"position":                "nullable|in:bottom-right,bottom-left,middle-right,middle-left",
		"label_title_pl":          "nullable|string|max:120",
		"label_title_en":          "nullable|string|max:120",
		"label_placeholder_pl":    "nullable|string|max:200",
		"label_placeholder_en":    "nullable|string|max:200",
		"label_success_pl":        "nullable|string|max:200",
		"label_success_en":        "nullable|string|max:200",
		"g15office_task_status":   "nullable|string|max:100",
		"g15office_task_priority": "nullable|in:low,normal,high,urgent",
	}
}

// BeforeSave keeps a widget key on the row: a row created without one (the
// admin form's first save, Instance) or saved with an emptied one gets a
// fresh key. The key is public (it ships in the embed snippet) but must be
// unguessable and unique per install.
func (s *Settings) BeforeSave(*gorm.DB) error {
	if strings.TrimSpace(s.WidgetKey) != "" {
		return nil
	}
	key, err := NewWidgetKey()
	if err != nil {
		return err
	}
	s.WidgetKey = key
	return nil
}

// DefaultSettings returns the row Settings::initSettingsData builds, without
// a widget key (BeforeSave generates it).
func DefaultSettings() Settings {
	str := func(s string) *string { return &s }
	return Settings{
		ID:                    SettingsID,
		Enabled:               true,
		AllowHide:             false,
		Position:              str("bottom-right"),
		G15OfficeTaskPriority: str("normal"),
		LabelTitlePL:          str("Zgłoś opinię"),
		LabelTitleEN:          str("Send feedback"),
		LabelPlaceholderPL:    str("Co poszło nie tak?"),
		LabelPlaceholderEN:    str("What went wrong?"),
		LabelSuccessPL:        str("Dzięki za zgłoszenie!"),
		LabelSuccessEN:        str("Thanks for the feedback!"),
	}
}

// Instance is Settings::instance(): the settings row, created with the
// defaults (and a new widget key) on first access, as WinterCMS persists
// initSettingsData. Two first accesses at once keep one row.
func Instance(ctx context.Context, db *gorm.DB) (*Settings, error) {
	if db == nil {
		return nil, errors.New("feedback: database is not configured")
	}
	q := db.WithContext(ctx)
	read := func() (*Settings, error) {
		var rows []Settings
		if err := q.Where("id = ?", SettingsID).Limit(1).Find(&rows).Error; err != nil {
			return nil, err
		}
		if len(rows) == 0 {
			return nil, nil
		}
		return &rows[0], nil
	}
	s, err := read()
	if err != nil || s != nil {
		return s, err
	}
	fresh := DefaultSettings()
	if err := q.Clauses(clause.OnConflict{DoNothing: true}).Create(&fresh).Error; err != nil {
		return nil, err
	}
	s, err = read()
	if err == nil && s == nil {
		err = errors.New("feedback: the settings row was not created")
	}
	return s, err
}

// widgetKeyAlphabet is Str::random's alphabet.
const widgetKeyAlphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"

// NewWidgetKey returns wk_ plus 32 random letters and digits from
// crypto/rand ('wk_' . Str::random(32)).
func NewWidgetKey() (string, error) {
	var b strings.Builder
	b.WriteString("wk_")
	max := big.NewInt(int64(len(widgetKeyAlphabet)))
	for i := 0; i < 32; i++ {
		n, err := rand.Int(rand.Reader, max)
		if err != nil {
			return "", err
		}
		b.WriteByte(widgetKeyAlphabet[n.Int64()])
	}
	return b.String(), nil
}

// Labels is the label triple of the config response.
type Labels struct {
	Title       *string `json:"title"`
	Placeholder *string `json:"placeholder"`
	Success     *string `json:"success"`
}

// LabelsForLocale is Settings::labelsForLocale: the English labels for
// "en", the Polish ones for anything else.
func (s *Settings) LabelsForLocale(locale string) Labels {
	if locale == "en" {
		return Labels{Title: s.LabelTitleEN, Placeholder: s.LabelPlaceholderEN, Success: s.LabelSuccessEN}
	}
	return Labels{Title: s.LabelTitlePL, Placeholder: s.LabelPlaceholderPL, Success: s.LabelSuccessPL}
}

// AllowedOriginHosts is Settings::getAllowedOriginHosts: one entry per line
// of allowed_origins, trimmed, blank lines (and a lone "0", which PHP's
// filter() drops) skipped, each reduced to its URL host when it has one
// (PHP parse_url) or kept as written, lower-cased, without duplicates, in
// order. https://example.com/ and //example.com give example.com, while
// example.com/ stays example.com/ and so matches no Origin, as in PHP.
func (s *Settings) AllowedOriginHosts() []string {
	if s == nil || s.AllowedOrigins == nil {
		return nil
	}
	lines := strings.FieldsFunc(*s.AllowedOrigins, func(r rune) bool { return r == '\r' || r == '\n' })
	out := make([]string, 0, len(lines))
	seen := map[string]bool{}
	for _, line := range lines {
		line = strings.Trim(line, " \t\n\r\x00\x0B")
		if line == "" || line == "0" {
			continue
		}
		host, ok := URLHost(line)
		if !ok || host == "" {
			host = line
		}
		host = ASCIILower(host)
		if seen[host] {
			continue
		}
		seen[host] = true
		out = append(out, host)
	}
	return out
}

// URLHost is parse_url($s, PHP_URL_HOST) for the inputs an Origin header or
// an allowed-origins line holds. With a scheme (or a leading //) the host
// is the authority without user info and port; an IPv6 literal keeps its
// brackets; a port that is not a number up to 65535 makes the whole URL
// invalid. Without a scheme, PHP reads "host:port" (optionally followed by
// a path) as a host and a port. ok is false when PHP returns null or false.
func URLHost(s string) (string, bool) {
	rest, hasAuthority := "", false
	if strings.HasPrefix(s, "//") {
		rest, hasAuthority = s[2:], true
	} else if i := strings.Index(s, "://"); i > 0 && validScheme(s[:i]) {
		rest, hasAuthority = s[i+3:], true
	}
	if !hasAuthority {
		return hostPortOnly(s)
	}
	authority := rest
	if i := strings.IndexAny(authority, "/?#"); i >= 0 {
		authority = authority[:i]
	}
	if i := strings.LastIndex(authority, "@"); i >= 0 {
		authority = authority[i+1:]
	}
	host, port := authority, ""
	if strings.HasPrefix(authority, "[") {
		end := strings.Index(authority, "]")
		if end < 0 {
			return "", false
		}
		host, port = authority[:end+1], strings.TrimPrefix(authority[end+1:], ":")
		if authority[end+1:] != "" && !strings.HasPrefix(authority[end+1:], ":") {
			return "", false
		}
	} else if i := strings.LastIndex(authority, ":"); i >= 0 {
		host, port = authority[:i], authority[i+1:]
	}
	if port != "" && !validPort(port) {
		return "", false
	}
	if host == "" {
		return "", false
	}
	return host, true
}

// ASCIILower is PHP 8 strtolower: ASCII letters only.
func ASCIILower(s string) string {
	b := []byte(s)
	for i, c := range b {
		if c >= 'A' && c <= 'Z' {
			b[i] = c + 'a' - 'A'
		}
	}
	return string(b)
}

func hostPortOnly(s string) (string, bool) {
	i := strings.Index(s, ":")
	if i <= 0 {
		return "", false
	}
	host, rest := s[:i], s[i+1:]
	if strings.ContainsAny(host, "/?#") {
		return "", false
	}
	port := rest
	if j := strings.Index(rest, "/"); j >= 0 {
		port = rest[:j]
	}
	if port == "" || !validPort(port) {
		return "", false
	}
	return host, true
}

func validScheme(s string) bool {
	for i, r := range s {
		switch {
		case r >= 'a' && r <= 'z', r >= 'A' && r <= 'Z':
		case i > 0 && (r >= '0' && r <= '9' || r == '+' || r == '-' || r == '.'):
		default:
			return false
		}
	}
	return s != ""
}

func validPort(s string) bool {
	for _, r := range s {
		if r < '0' || r > '9' {
			return false
		}
	}
	n, err := strconv.Atoi(s)
	return err == nil && n <= 65535
}

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