package database

import (
	"strconv"

	"gorm.io/gorm"
)

const (
	// DefaultRetentionDays is the event retention period applied to a
	// webhook created without an explicit retention value. It is the
	// single source of truth for that policy and must stay in sync
	// with the `gorm:"default:30"` column default on
	// Webhook.RetentionDays below; a struct tag cannot reference a
	// constant, so a test asserts the two agree.
	DefaultRetentionDays = 30

	// RetentionForeverDays is the sentinel RetentionDays value meaning
	// "retain events forever". Users express that intent as 0, which
	// Webhook.BeforeSave rewrites to this value: the column default
	// substitutes DefaultRetentionDays for a zero value at insert
	// time, so a zero can never survive a round trip to the database.
	// Nothing outside this file may hardcode the number.
	RetentionForeverDays = 365 * 1000
)

// Webhook represents a webhook processing unit that groups entrypoints and targets
//
// The receiver kinds below are deliberately mixed. BeforeSave has to
// take a pointer because it mutates the record, and GORM only invokes
// hooks declared that way. RetainsForever and RetentionLabel have to
// take values because html/template calls them on webhooks held in a
// template data map, which reflection cannot address; a pointer
// receiver there fails at render time rather than at compile time.
//
//nolint:recvcheck // GORM needs a pointer hook; templates need values.
type Webhook struct {
	BaseModel

	UserID      string `gorm:"type:uuid;not null" json:"userId"`
	Name        string `gorm:"not null"           json:"name"`
	Description string `json:"description"`

	// RetentionDays is the number of days to retain events. A value of
	// RetentionForeverDays means retain forever. The column default
	// must equal DefaultRetentionDays.
	RetentionDays int `gorm:"default:30" json:"retentionDays"`

	// Relations
	User        User         `json:"user,omitzero"`
	Entrypoints []Entrypoint `json:"entrypoints,omitempty"`
	Targets     []Target     `json:"targets,omitempty"`
}

// BeforeSave normalises RetentionDays on every insert and update. A
// non-positive value is the user's way of asking for "retain forever",
// which is stored as the RetentionForeverDays sentinel.
//
// This has to happen in a hook rather than at the call sites. GORM
// substitutes the column default (DefaultRetentionDays) for a zero
// value while building the insert statement, which runs after
// BeforeSave; rewriting any later than this loses that race and the
// row lands at 30 days. Living on the model also means a future call
// site — a REST API, a fixture, a migration — cannot bypass it.
func (w *Webhook) BeforeSave(_ *gorm.DB) error {
	if w.RetentionDays <= 0 {
		w.RetentionDays = RetentionForeverDays
	}

	return nil
}

// RetainsForever reports whether this webhook's events are kept
// indefinitely. It accepts the RetentionForeverDays sentinel written by
// BeforeSave and, defensively, the non-positive values that rows
// written before the sentinel existed may still carry.
func (w Webhook) RetainsForever() bool {
	return w.RetentionDays <= 0 ||
		w.RetentionDays >= RetentionForeverDays
}

// RetentionLabel returns the webhook's retention policy as display
// text, so that no template has to know about the sentinel value.
func (w Webhook) RetentionLabel() string {
	if w.RetainsForever() {
		return "forever"
	}

	if w.RetentionDays == 1 {
		return "1 day"
	}

	return strconv.Itoa(w.RetentionDays) + " days"
}