package licensing

import (
	"sort"
	"time"
)

// Claims represents the JWT claims in a Pulse Pro license.
type Claims struct {
	// License ID (unique identifier)
	LicenseID string `json:"lid"`

	// Email of the license holder
	Email string `json:"email"`

	// License tier (pro, pro_annual, lifetime, msp, enterprise)
	Tier Tier `json:"tier"`

	// Issued at (Unix timestamp)
	IssuedAt int64 `json:"iat"`

	// Expires at (Unix timestamp, 0 for lifetime)
	ExpiresAt int64 `json:"exp,omitempty"`

	// LicensePeriodEnd is the paid entitlement period end. Activation grants use
	// a short ExpiresAt lease for enforcement; this field preserves the billing
	// period shown in status responses when the grant carries it.
	LicensePeriodEnd int64 `json:"license_period_end,omitempty"`

	// Features explicitly granted (optional, tier implies features)
	Features []string `json:"features,omitempty"`

	// Max guests (0 = unlimited)
	MaxGuests int `json:"max_guests,omitempty"`

	// Max users (0 = unlimited). A seat limit, not a legacy volume cap:
	// the self-hosted commercial volume scrub never strips it.
	MaxUsers int `json:"max_users,omitempty"`

	// Entitlement primitives (B1) - when present, these override tier-based derivation.
	// When absent (nil/empty), entitlements are derived from Tier + existing fields.
	Capabilities  []string          `json:"capabilities,omitempty"`
	Limits        map[string]int64  `json:"limits,omitempty"`
	MetersEnabled []string          `json:"meters_enabled,omitempty"`
	PlanVersion   string            `json:"plan_version,omitempty"`
	SubState      SubscriptionState `json:"subscription_state,omitempty"`

	// EntitlementSigningPublicKey binds a provider-operated control plane's
	// entitlement lease signing key (base64 Ed25519 public key) to this
	// license. Hosted entitlement leases signed by the bound key chain back
	// to the embedded Pulse trust root through this license, so release
	// builds can verify provider-minted leases without trusting environment
	// wiring. Only meaningful on MSP-tier licenses.
	EntitlementSigningPublicKey string `json:"entitlement_signing_public_key,omitempty"`

	// CoreMonitoringUncapped is a local runtime marker used when a self-hosted
	// activation/grant should remain uncapped even if stale legacy limit fields
	// are still present in the persisted claims. It is intentionally excluded
	// from the JWT/storage wire contract.
	CoreMonitoringUncapped bool `json:"-"`
}

// EffectiveCapabilities returns explicit capabilities when present; otherwise tier-derived capabilities.
func (c Claims) EffectiveCapabilities() []string {
	if c.Capabilities != nil && len(c.Capabilities) > 0 {
		return c.Capabilities
	}
	return DeriveCapabilitiesFromTier(c.Tier, c.Features)
}

// EffectiveLimits returns explicit limits when present; otherwise limits derived from legacy fields.
func (c Claims) EffectiveLimits() map[string]int64 {
	limits := NormalizeMonitoredSystemLimits(c.Limits)
	stripSelfHostedCommercialVolumeCaps(limits, c.EntitlementPlanVersion(), c.Tier, c.CoreMonitoringUncapped)
	if len(limits) == 0 {
		limits = make(map[string]int64)
		if c.MaxGuests > 0 {
			limits["max_guests"] = int64(c.MaxGuests)
		}
		if c.MaxUsers > 0 {
			limits[MaxUsersLicenseGateKey] = int64(c.MaxUsers)
		}
		stripSelfHostedCommercialVolumeCaps(limits, c.EntitlementPlanVersion(), c.Tier, c.CoreMonitoringUncapped)
	}
	return limits
}

// EntitlementMetersEnabled returns metering keys for evaluator sources.
func (c *Claims) EntitlementMetersEnabled() []string {
	if c == nil {
		return nil
	}
	return c.MetersEnabled
}

// EntitlementPlanVersion returns plan metadata for evaluator sources.
func (c *Claims) EntitlementPlanVersion() string {
	if c == nil {
		return ""
	}
	return CanonicalizePlanVersion(c.PlanVersion)
}

// EntitlementSubscriptionState returns normalized subscription state for evaluator sources.
func (c *Claims) EntitlementSubscriptionState() SubscriptionState {
	if c == nil || c.SubState == "" {
		return SubStateActive
	}
	return c.SubState
}

// License represents a validated Pulse Pro license.
type License struct {
	// Raw JWT token
	Raw string `json:"-"`

	// Validated claims
	Claims Claims `json:"claims"`

	// Validation metadata
	ValidatedAt time.Time `json:"validated_at"`

	// Grace period end (if license was validated during grace period)
	GracePeriodEnd *time.Time `json:"grace_period_end,omitempty"`
}

// IsExpired checks if the license has expired.
func (l *License) IsExpired() bool {
	if l.Claims.ExpiresAt == 0 {
		return false // Lifetime license never expires
	}
	return time.Now().Unix() > l.Claims.ExpiresAt
}

// IsLifetime returns true if this is a lifetime license.
func (l *License) IsLifetime() bool {
	return l.Claims.ExpiresAt == 0 || l.Claims.Tier == TierLifetime
}

// DaysRemaining returns the number of days until expiration.
// Returns -1 for lifetime licenses.
func (l *License) DaysRemaining() int {
	if l.IsLifetime() {
		return -1
	}
	remaining := time.Until(time.Unix(l.Claims.ExpiresAt, 0))
	if remaining < 0 {
		return 0
	}
	return int(remaining.Hours() / 24)
}

// ExpiresAt returns the expiration time, or nil for lifetime.
func (l *License) ExpiresAt() *time.Time {
	if l.IsLifetime() {
		return nil
	}
	t := time.Unix(l.Claims.ExpiresAt, 0)
	return &t
}

// LicensePeriodDaysRemaining returns days remaining for user-facing license
// status. It uses the paid entitlement period when present and falls back to
// the grant/JWT expiration for legacy licenses and older grants.
func (l *License) LicensePeriodDaysRemaining() int {
	if l.IsLifetime() {
		return -1
	}
	expiresAt := l.Claims.LicensePeriodEnd
	if expiresAt == 0 {
		expiresAt = l.Claims.ExpiresAt
	}
	remaining := time.Until(time.Unix(expiresAt, 0))
	if remaining < 0 {
		return 0
	}
	return int(remaining.Hours() / 24)
}

// LicensePeriodExpiresAt returns the user-facing license period end. Short
// activation grant expiry remains available through ExpiresAt for enforcement.
func (l *License) LicensePeriodExpiresAt() *time.Time {
	if l.IsLifetime() {
		return nil
	}
	expiresAt := l.Claims.LicensePeriodEnd
	if expiresAt == 0 {
		expiresAt = l.Claims.ExpiresAt
	}
	t := time.Unix(expiresAt, 0)
	return &t
}

// HasFeature checks if the license grants a specific feature.
func (l *License) HasFeature(feature string) bool {
	for _, capability := range l.Claims.EffectiveCapabilities() {
		if capability == feature {
			return true
		}
	}
	return false
}

// AllFeatures returns all features granted by this license.
func (l *License) AllFeatures() []string {
	features := append([]string(nil), l.Claims.EffectiveCapabilities()...)
	sort.Strings(features)
	return features
}

// LicenseState represents the current state of the license.
type LicenseState string

const (
	LicenseStateNone        LicenseState = "none"
	LicenseStateActive      LicenseState = "active"
	LicenseStateExpired     LicenseState = "expired"
	LicenseStateGracePeriod LicenseState = "grace_period"
)

// LicenseStatus is the JSON response for license status API.
type LicenseStatus struct {
	Valid           bool                          `json:"valid"`
	Tier            Tier                          `json:"tier"`
	PlanVersion     string                        `json:"plan_version,omitempty"`
	Email           string                        `json:"email,omitempty"`
	ExpiresAt       *string                       `json:"expires_at,omitempty"`
	IsLifetime      bool                          `json:"is_lifetime"`
	DaysRemaining   int                           `json:"days_remaining"`
	Features        []string                      `json:"features"`
	MaxGuests       int                           `json:"max_guests,omitempty"`
	InGracePeriod   bool                          `json:"in_grace_period,omitempty"`
	GracePeriodEnd  *string                       `json:"grace_period_end,omitempty"`
	Synchronization *LicenseSynchronizationStatus `json:"synchronization,omitempty"`
}

// LicenseSynchronizationStatus reports non-secret health for the
// installation-scoped commercial invalidation loop.
type LicenseSynchronizationStatus struct {
	Running             bool    `json:"running"`
	Healthy             bool    `json:"healthy"`
	Stale               bool    `json:"stale"`
	LastAttemptAt       *string `json:"last_attempt_at,omitempty"`
	LastSuccessAt       *string `json:"last_success_at,omitempty"`
	NextCheckAt         *string `json:"next_check_at,omitempty"`
	ConsecutiveFailures int     `json:"consecutive_failures"`
}