package database

import (
	"time"

	"github.com/google/uuid"
	"gorm.io/gorm"
)

const (
	CAMPAIGN_RECIPIENT_TABLE_NAME = "campaign_recipients"
)

// CampaigReciever is gorm data model
// this model/table is primarily used to keep track of who and when should recieve a campaign
type CampaignRecipient struct {
	ID *uuid.UUID `gorm:"primary_key;not null;unique;type:uuid"`

	CreatedAt *time.Time `gorm:"not null;index;"`
	UpdatedAt *time.Time `gorm:"not null;index;"`

	Campaign   *Campaign
	CampaignID *uuid.UUID `gorm:"not null;type:uuid;uniqueIndex:idx_campaign_recipients_campaign_id_recipient_id;"`

	// CancelledAt *time.Time `gorm:"index;"`
	CancelledAt *time.Time `gorm:"index;"`

	// when it should be send
	SendAt *time.Time `gorm:"index;"`

	// when it was last attempted send
	LastAttemptAt *time.Time `gorm:"index;"`

	// when it was sent
	SentAt *time.Time `gorm:"index;"`

	// self-managed
	SelfManaged bool `gorm:"not null;default:false;"`

	// AnonymizedID is set when the recipient has been anonymized
	AnonymizedID *uuid.UUID `gorm:"type:uuid;"`
	Recipient    *Recipient
	// A null recipientID means that the data has been anonymized
	RecipientID *uuid.UUID `gorm:"type:uuid;index;uniqueIndex:idx_campaign_recipients_campaign_id_recipient_id;"`

	// NotableEventID is the most notable event for this recipient
	NotableEvent   *Event     `gorm:"foreignKey:NotableEventID;references:ID"`
	NotableEventID *uuid.UUID `gorm:"type:uuid;index"`

	// LureCode is the short identifier that appears in the lure URL instead of
	// the campaign recipient UUID, for example https://example.com/4H7K9QM2XR3T.
	// It is stored exactly as written and matched exactly, which is what lets an
	// operator pick a code such as Special-42 and get that link verbatim.
	//
	// Releasing a code sets this back to null. Nulling rather than flagging is
	// what keeps a reclaimed code from still showing against its former owner,
	// and it lets the unique index below need nothing but IS NOT NULL.
	LureCode *string `gorm:"type:varchar(64)"`
	// LureCodeCustom marks a code the operator set by hand. A custom code cannot
	// be told apart from a generated one by shape, so the distinction is stored.
	LureCodeCustom bool `gorm:"not null;default:false"`
}

func (CampaignRecipient) TableName() string {
	return CAMPAIGN_RECIPIENT_TABLE_NAME
}

// Migrate creates the partial unique index backing lure code allocation.
//
// The predicate has to exclude rows carrying no code, otherwise every recipient
// in a query mode campaign enters the index under the same value and the second
// insert fails. Because releasing a code nulls it, that single predicate also
// covers reuse: a released code leaves the index and is free to claim again.
//
// This is raw SQL rather than a gorm index tag because only the sqlite driver
// emits the WHERE clause. The generic migrator drops it, which would silently
// produce a full unique index and break reuse.
func (CampaignRecipient) Migrate(db *gorm.DB) error {
	// lure_code is the only code column this table carries. AutoMigrate adds
	// columns but never drops them, so any other lure column and its indexes are
	// removed here. errors are ignored because on a fresh install there is
	// nothing to drop.
	db.Exec(`DROP INDEX IF EXISTS idx_campaign_recipients_lure_code_lookup`)
	db.Exec(`DROP INDEX IF EXISTS idx_campaign_recipients_lure_code_released_at`)
	db.Exec(`DROP INDEX IF EXISTS idx_campaign_recipients_lure_code_folded`)
	db.Exec(`ALTER TABLE campaign_recipients DROP COLUMN lure_code_lookup`)
	db.Exec(`ALTER TABLE campaign_recipients DROP COLUMN lure_code_released_at`)
	db.Exec(`ALTER TABLE campaign_recipients DROP COLUMN lure_code_folded`)

	createIndex := func() error {
		return db.Exec(`CREATE UNIQUE INDEX IF NOT EXISTS idx_campaign_recipients_lure_code
			ON campaign_recipients (lure_code)
			WHERE lure_code IS NOT NULL`).Error
	}
	err := createIndex()
	if err == nil {
		return nil
	}

	// the index fails when two rows already hold the same code. keep the first
	// row for each code and release the rest, then build the index.
	//
	// this runs only after a failure, because the scan and grouping it needs
	// are too costly to pay on every startup.
	if dedupErr := db.Exec(`UPDATE campaign_recipients SET lure_code = NULL
		WHERE lure_code IS NOT NULL
		  AND rowid NOT IN (
		    SELECT MIN(rowid) FROM campaign_recipients
		    WHERE lure_code IS NOT NULL
		    GROUP BY lure_code
		  )`).Error; dedupErr != nil {
		return dedupErr
	}
	return createIndex()
}