package store

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"strings"
	"time"

	"github.com/jackc/pgx/v5"
)

// GatewaySettingsKey is the app_settings row backing the gateway's own settings.
const GatewaySettingsKey = "gateway_settings"

// GatewaySettings is the handful of server-level decisions an operator can change
// without a redeployment.
//
// Most fields are an *override* of the value the container was started with, and their
// zero value means "whatever was deployed". That is the whole design: `.env` remains the
// configuration — it is what a fresh container comes up with, what deploy-server.ps1
// writes and what an operator locked out of the console still has — and this row is a
// runtime amendment to it, so the console can always show the deployed value beside the
// one in force and an operator can put a setting back by clearing it rather than by
// remembering what it used to be. NotificationDisplay is the exception: it is a native
// server policy with a Home-only default rather than an environment-backed value.
//
// A window that can legitimately be *off* therefore needs a value distinct from "not
// overridden", which is why the two alert windows and the health interval take -1 for off
// and 0 for deployed. A plain zero would make "turn this off" indistinguishable from
// "leave it alone", and the operator would find the setting quietly ignored.
type GatewaySettings struct {
	// Timezone is an IANA name. It decides the household's local day, which is what the
	// schedule rows, the hero rotation, the sign-in history and the first-use
	// notifications are all grouped by.
	Timezone string `json:"timezone"`
	// LogLevel is one of trace, debug, info, warn, error. It takes effect immediately on
	// the running process, which is the point of it being here: turning debug on to watch
	// something happen is worth nothing if it costs a restart of the thing being watched.
	LogLevel string `json:"logLevel"`
	// SessionIdleDays is how long a television may go unused before it is signed out.
	SessionIdleDays int `json:"sessionIdleDays"`
	// SonarrAlertMinutes and RadarrAlertMinutes are how long a "just aired" or "new movie
	// added" banner stays on offer to a television that was switched off at the time.
	SonarrAlertMinutes int `json:"sonarrAlertMinutes"`
	RadarrAlertMinutes int `json:"radarrAlertMinutes"`
	// NotificationDisplay is where informational banners may be drawn across every
	// viewer and television. It is server-owned rather than a per-viewer preference:
	// one household should not have different interruption rules on different sets.
	NotificationDisplay string `json:"notificationDisplay"`
	// EmbyHealthSeconds is how often the reachability probe asks Emby whether it is there.
	EmbyHealthSeconds int `json:"embyHealthSeconds"`
	// SlowRequestMillis is how long a request must take before its log line carries a
	// stage breakdown — Emby time, database time, cache outcome, gateway work. It is an
	// override worth having because the useful threshold is a property of the household
	// rather than of the build: an operator chasing one slow screen wants it at 100ms for
	// an evening and back at 500 afterwards, and neither is a redeployment.
	SlowRequestMillis int `json:"slowRequestMillis"`
	// LibrarySyncMinutes is how often the catalogue sweep asks Emby what changed.
	//
	// It is an override worth having because the answer now depends on the household's
	// wiring rather than on the gateway: with both *arr webhooks configured, a new file is
	// in the catalogue within a minute of landing and the sweep is reconciliation for
	// media Sonarr and Radarr do not manage — six hours rather than one. With no webhooks
	// it is still the only way anything is discovered and must stay frequent.
	LibrarySyncMinutes int `json:"librarySyncMinutes"`

	UpdatedAt time.Time `json:"updatedAt"`
	UpdatedBy string    `json:"updatedBy,omitempty"`
}

// GatewaySettingsOff is the value a duration-like override takes to mean "switched off",
// as distinct from the zero that means "use the deployed value".
const GatewaySettingsOff = -1

// GatewayLogLevels is the vocabulary the console offers, in order of severity. It is here
// rather than in the API because normalisation has to refuse a level nothing can parse,
// and refusing is worth nothing if the list it refuses against lives somewhere else.
var GatewayLogLevels = []string{"trace", "debug", "info", "warn", "error"}

const (
	NotificationDisplayEverywhere = "everywhere"
	NotificationDisplayHomeOnly   = "home_only"
	NotificationDisplayOff        = "off"
)

// GatewayNotificationDisplays is the complete wire vocabulary, served to the console so
// it cannot offer a value the gateway would refuse.
var GatewayNotificationDisplays = []string{
	NotificationDisplayEverywhere,
	NotificationDisplayHomeOnly,
	NotificationDisplayOff,
}

func normalizeGatewaySettings(settings GatewaySettings) GatewaySettings {
	settings.Timezone = strings.TrimSpace(settings.Timezone)
	if settings.Timezone != "" {
		// A timezone that will not load is dropped rather than stored: the alternative is
		// a row that every later read has to fail on, and the failure would surface as a
		// household whose idea of "today" quietly reverted with nothing saying why.
		if _, err := time.LoadLocation(settings.Timezone); err != nil {
			settings.Timezone = ""
		}
	}
	settings.LogLevel = strings.ToLower(strings.TrimSpace(settings.LogLevel))
	if settings.LogLevel != "" && !containsString(GatewayLogLevels, settings.LogLevel) {
		settings.LogLevel = ""
	}
	settings.SessionIdleDays = clampOverride(settings.SessionIdleDays, 1, 3650, false)
	settings.SonarrAlertMinutes = clampOverride(settings.SonarrAlertMinutes, 1, 24*60, true)
	settings.RadarrAlertMinutes = clampOverride(settings.RadarrAlertMinutes, 1, 7*24*60, true)
	settings.NotificationDisplay = strings.ToLower(strings.TrimSpace(settings.NotificationDisplay))
	if !containsString(GatewayNotificationDisplays, settings.NotificationDisplay) {
		// Missing covers both a new installation and a row written by an older gateway.
		// Unknown is equally conservative: silence from the setting must never authorise
		// an interruption over active playback.
		settings.NotificationDisplay = NotificationDisplayHomeOnly
	}
	settings.EmbyHealthSeconds = clampOverride(settings.EmbyHealthSeconds, 10, 3600, true)
	// The floor is 1ms rather than 0 because "breakdown on everything" is a real thing to
	// want for a few minutes, and off is a real thing to want too — this is the one
	// setting here whose switched-off state costs nothing but a column of text.
	settings.SlowRequestMillis = clampOverride(settings.SlowRequestMillis, 1, 60000, true)
	// A day is the ceiling rather than a week: however well the webhooks are working, the
	// sweep is the only thing that ever notices a file somebody moved by hand.
	settings.LibrarySyncMinutes = clampOverride(settings.LibrarySyncMinutes, 5, 24*60, true)
	return settings
}

// clampOverride keeps 0 meaning "deployed" and, where the setting can be switched off,
// keeps every negative number meaning off rather than only -1 — an operator typing -5 has
// said the same thing, and storing it verbatim would produce a second value with the same
// meaning that every reader would have to know about.
func clampOverride(value, low, high int, offAllowed bool) int {
	if value == 0 {
		return 0
	}
	if value < 0 {
		if offAllowed {
			return GatewaySettingsOff
		}
		return 0
	}
	return max(low, min(value, high))
}

func containsString(values []string, value string) bool {
	for _, candidate := range values {
		if candidate == value {
			return true
		}
	}
	return false
}

func (s *Store) GatewaySettings(ctx context.Context) (GatewaySettings, error) {
	var raw []byte
	err := s.pool.QueryRow(ctx,
		`SELECT value FROM app_settings WHERE key = $1`, GatewaySettingsKey).Scan(&raw)
	if errors.Is(err, pgx.ErrNoRows) {
		return normalizeGatewaySettings(GatewaySettings{}), nil
	}
	if err != nil {
		return GatewaySettings{}, fmt.Errorf("store: read gateway settings: %w", err)
	}
	var settings GatewaySettings
	if err := json.Unmarshal(raw, &settings); err != nil {
		return GatewaySettings{}, fmt.Errorf("store: decode gateway settings: %w", err)
	}
	return normalizeGatewaySettings(settings), nil
}

// SetGatewaySettings writes the overrides and returns what was actually stored, because
// normalisation can refuse a value and the console must show what is in force rather than
// what was typed.
func (s *Store) SetGatewaySettings(
	ctx context.Context, settings GatewaySettings,
) (GatewaySettings, error) {
	settings = normalizeGatewaySettings(settings)
	settings.UpdatedAt = time.Now().UTC()
	raw, err := json.Marshal(settings)
	if err != nil {
		return GatewaySettings{}, err
	}
	_, err = s.pool.Exec(ctx, `
		INSERT INTO app_settings (key, value, updated_at)
		VALUES ($1, $2::jsonb, now())
		ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value, updated_at = now()`,
		GatewaySettingsKey, string(raw))
	if err != nil {
		return GatewaySettings{}, fmt.Errorf("store: write gateway settings: %w", err)
	}
	return settings, nil
}