// Package store persists SMART snapshots, alert state and self-test bookkeeping in SQLite.
package store

import (
	"database/sql"
	"encoding/json"
	"time"

	_ "modernc.org/sqlite"

	"nasmon/internal/collect"
)

type Store struct{ db *sql.DB }

const schema = `
CREATE TABLE IF NOT EXISTS smart_snapshots (
	id INTEGER PRIMARY KEY,
	ts INTEGER NOT NULL,
	serial TEXT NOT NULL,
	device TEXT NOT NULL,
	temp_c INTEGER,
	healthy INTEGER,
	power_on_hours INTEGER,
	data TEXT NOT NULL
);
CREATE INDEX IF NOT EXISTS smart_snapshots_serial_ts ON smart_snapshots(serial, ts);

CREATE TABLE IF NOT EXISTS alerts (
	id INTEGER PRIMARY KEY,
	key TEXT NOT NULL,
	level TEXT NOT NULL,
	title TEXT NOT NULL,
	detail TEXT NOT NULL,
	opened_at INTEGER NOT NULL,
	resolved_at INTEGER,
	last_notified_at INTEGER,
	acked_at INTEGER
);
CREATE INDEX IF NOT EXISTS alerts_key_open ON alerts(key, resolved_at);

CREATE TABLE IF NOT EXISTS selftest_runs (
	serial TEXT NOT NULL,
	kind TEXT NOT NULL,
	started_at INTEGER NOT NULL,
	PRIMARY KEY (serial, kind)
);

CREATE TABLE IF NOT EXISTS disks_seen (
	serial TEXT PRIMARY KEY,
	model TEXT NOT NULL,
	device TEXT NOT NULL,
	last_seen INTEGER NOT NULL,
	missing_acked INTEGER NOT NULL DEFAULT 0
);
`

func Open(path string) (*Store, error) {
	db, err := sql.Open("sqlite", path+"?_pragma=journal_mode(WAL)&_pragma=busy_timeout(5000)")
	if err != nil {
		return nil, err
	}
	db.SetMaxOpenConns(1)
	if _, err := db.Exec(schema); err != nil {
		db.Close()
		return nil, err
	}
	if err := migrate(db); err != nil {
		db.Close()
		return nil, err
	}
	return &Store{db: db}, nil
}

// migrate adds columns introduced after the first release.
func migrate(db *sql.DB) error {
	rows, err := db.Query(`PRAGMA table_info(alerts)`)
	if err != nil {
		return err
	}
	defer rows.Close()
	have := map[string]bool{}
	for rows.Next() {
		var cid int
		var name, typ string
		var notnull, pk int
		var dflt sql.NullString
		if err := rows.Scan(&cid, &name, &typ, &notnull, &dflt, &pk); err != nil {
			return err
		}
		have[name] = true
	}
	if err := rows.Err(); err != nil {
		return err
	}
	if !have["acked_at"] {
		if _, err := db.Exec(`ALTER TABLE alerts ADD COLUMN acked_at INTEGER`); err != nil {
			return err
		}
	}
	return nil
}

func (s *Store) Close() error { return s.db.Close() }

// ---- SMART snapshots

func (s *Store) AddSmart(sm collect.Smart) error {
	if sm.Serial == "" {
		return nil
	}
	b, err := json.Marshal(sm)
	if err != nil {
		return err
	}
	_, err = s.db.Exec(`INSERT INTO smart_snapshots(ts, serial, device, temp_c, healthy, power_on_hours, data) VALUES(?,?,?,?,?,?,?)`,
		sm.CheckedAt.Unix(), sm.Serial, sm.Device, sm.TempC, sm.Healthy, sm.PowerOnHrs, string(b))
	return err
}

// LastSmart returns the most recent stored snapshot for a serial.
func (s *Store) LastSmart(serial string) (*collect.Smart, error) {
	var data string
	err := s.db.QueryRow(`SELECT data FROM smart_snapshots WHERE serial=? ORDER BY ts DESC LIMIT 1`, serial).Scan(&data)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	var sm collect.Smart
	if err := json.Unmarshal([]byte(data), &sm); err != nil {
		return nil, err
	}
	return &sm, nil
}

type SmartPoint struct {
	T       int64 `json:"t"`
	TempC   int   `json:"temp_c"`
	Healthy bool  `json:"healthy"`
	Hours   int64 `json:"hours"`
	Realloc int64 `json:"realloc"` // attr 5 raw or NVMe media errors
	Pending int64 `json:"pending"` // attr 197 raw
	CRC     int64 `json:"crc"`     // attr 199 raw
}

// SmartHistory returns compact per-snapshot points since t.
func (s *Store) SmartHistory(serial string, since time.Time) ([]SmartPoint, error) {
	rows, err := s.db.Query(`SELECT ts, data FROM smart_snapshots WHERE serial=? AND ts>=? ORDER BY ts`, serial, since.Unix())
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []SmartPoint
	for rows.Next() {
		var ts int64
		var data string
		if err := rows.Scan(&ts, &data); err != nil {
			return nil, err
		}
		var sm collect.Smart
		if json.Unmarshal([]byte(data), &sm) != nil {
			continue
		}
		p := SmartPoint{T: ts, TempC: sm.TempC, Healthy: sm.Healthy, Hours: sm.PowerOnHrs}
		if a, ok := sm.Attr(5); ok {
			p.Realloc = a.Raw
		} else if sm.NVMe != nil {
			p.Realloc = sm.NVMe.MediaErrors
		}
		if a, ok := sm.Attr(197); ok {
			p.Pending = a.Raw
		}
		if a, ok := sm.Attr(199); ok {
			p.CRC = a.Raw
		}
		out = append(out, p)
	}
	return out, rows.Err()
}

func (s *Store) PruneSmart(olderThan time.Time) error {
	_, err := s.db.Exec(`DELETE FROM smart_snapshots WHERE ts<?`, olderThan.Unix())
	return err
}

// ---- alerts

type Alert struct {
	ID             int64      `json:"id"`
	Key            string     `json:"key"`
	Level          string     `json:"level"`
	Title          string     `json:"title"`
	Detail         string     `json:"detail"`
	OpenedAt       time.Time  `json:"opened_at"`
	ResolvedAt     *time.Time `json:"resolved_at,omitempty"`
	LastNotifiedAt *time.Time `json:"last_notified_at,omitempty"`
	AckedAt        *time.Time `json:"acked_at,omitempty"`
}

// Acked reports whether the alert was acknowledged by the user.
func (a Alert) Acked() bool { return a.AckedAt != nil }

func scanAlert(sc interface{ Scan(...any) error }) (Alert, error) {
	var a Alert
	var opened int64
	var resolved, notified, acked sql.NullInt64
	err := sc.Scan(&a.ID, &a.Key, &a.Level, &a.Title, &a.Detail, &opened, &resolved, &notified, &acked)
	if err != nil {
		return a, err
	}
	if acked.Valid {
		t := time.Unix(acked.Int64, 0)
		a.AckedAt = &t
	}
	a.OpenedAt = time.Unix(opened, 0)
	if resolved.Valid {
		t := time.Unix(resolved.Int64, 0)
		a.ResolvedAt = &t
	}
	if notified.Valid {
		t := time.Unix(notified.Int64, 0)
		a.LastNotifiedAt = &t
	}
	return a, nil
}

const alertCols = `id, key, level, title, detail, opened_at, resolved_at, last_notified_at, acked_at`

// OpenAlerts returns every unresolved alert, acknowledged ones included.
func (s *Store) OpenAlerts() ([]Alert, error) {
	return s.queryAlerts(`SELECT ` + alertCols + ` FROM alerts WHERE resolved_at IS NULL ORDER BY opened_at DESC`)
}

// ActiveAlerts returns unresolved alerts that were not acknowledged — what the
// dashboard and the nav badge show.
func (s *Store) ActiveAlerts() ([]Alert, error) {
	return s.queryAlerts(`SELECT ` + alertCols + ` FROM alerts WHERE resolved_at IS NULL AND acked_at IS NULL ORDER BY opened_at DESC`)
}

// RecentAlerts returns all open alerts plus those resolved at or after
// resolvedSince (zero time = every resolved alert), newest first.
func (s *Store) RecentAlerts(limit int, resolvedSince time.Time) ([]Alert, error) {
	return s.queryAlerts(`SELECT `+alertCols+` FROM alerts WHERE resolved_at IS NULL OR resolved_at>=? ORDER BY opened_at DESC LIMIT ?`,
		resolvedSince.Unix(), limit)
}

// CountResolvedBefore counts resolved alerts hidden by the default alerts view.
func (s *Store) CountResolvedBefore(t time.Time) (int, error) {
	var n int
	err := s.db.QueryRow(`SELECT COUNT(*) FROM alerts WHERE resolved_at IS NOT NULL AND resolved_at<?`, t.Unix()).Scan(&n)
	return n, err
}

func (s *Store) GetAlert(id int64) (*Alert, error) {
	a, err := scanAlert(s.db.QueryRow(`SELECT `+alertCols+` FROM alerts WHERE id=?`, id))
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	return &a, nil
}

func (s *Store) AckAlert(id int64, now time.Time) error {
	_, err := s.db.Exec(`UPDATE alerts SET acked_at=? WHERE id=? AND resolved_at IS NULL`, now.Unix(), id)
	return err
}

// UnackAlert shows an acknowledged alert again (user action, no new mail).
func (s *Store) UnackAlert(id int64) error {
	_, err := s.db.Exec(`UPDATE alerts SET acked_at=NULL WHERE id=?`, id)
	return err
}

// ReraiseAlert clears the acknowledgement and the delivery mark, so the alert
// is mailed again as new.
func (s *Store) ReraiseAlert(id int64) error {
	_, err := s.db.Exec(`UPDATE alerts SET acked_at=NULL, last_notified_at=NULL WHERE id=?`, id)
	return err
}

// DeleteAlert removes a resolved alert from the log; open alerts are kept.
func (s *Store) DeleteAlert(id int64) error {
	_, err := s.db.Exec(`DELETE FROM alerts WHERE id=? AND resolved_at IS NOT NULL`, id)
	return err
}

// PruneAlerts drops resolved alerts older than olderThan.
func (s *Store) PruneAlerts(olderThan time.Time) error {
	_, err := s.db.Exec(`DELETE FROM alerts WHERE resolved_at IS NOT NULL AND resolved_at<?`, olderThan.Unix())
	return err
}

func (s *Store) queryAlerts(q string, args ...any) ([]Alert, error) {
	rows, err := s.db.Query(q, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []Alert
	for rows.Next() {
		a, err := scanAlert(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, a)
	}
	return out, rows.Err()
}

func (s *Store) OpenAlert(key, level, title, detail string, now time.Time) (Alert, error) {
	res, err := s.db.Exec(`INSERT INTO alerts(key, level, title, detail, opened_at) VALUES(?,?,?,?,?)`,
		key, level, title, detail, now.Unix())
	if err != nil {
		return Alert{}, err
	}
	id, _ := res.LastInsertId()
	return Alert{ID: id, Key: key, Level: level, Title: title, Detail: detail, OpenedAt: now}, nil
}

// UpdateAlertDetail refreshes level/detail of an open alert.
func (s *Store) UpdateAlertDetail(id int64, level, detail string) error {
	_, err := s.db.Exec(`UPDATE alerts SET level=?, detail=? WHERE id=?`, level, detail, id)
	return err
}

func (s *Store) ResolveAlert(id int64, now time.Time) error {
	_, err := s.db.Exec(`UPDATE alerts SET resolved_at=? WHERE id=?`, now.Unix(), id)
	return err
}

func (s *Store) MarkNotified(ids []int64, now time.Time) error {
	for _, id := range ids {
		if _, err := s.db.Exec(`UPDATE alerts SET last_notified_at=? WHERE id=?`, now.Unix(), id); err != nil {
			return err
		}
	}
	return nil
}

// ---- self-tests

func (s *Store) LastSelfTest(serial, kind string) (time.Time, error) {
	var ts int64
	err := s.db.QueryRow(`SELECT started_at FROM selftest_runs WHERE serial=? AND kind=?`, serial, kind).Scan(&ts)
	if err == sql.ErrNoRows {
		return time.Time{}, nil
	}
	return time.Unix(ts, 0), err
}

func (s *Store) SetSelfTest(serial, kind string, at time.Time) error {
	_, err := s.db.Exec(`INSERT INTO selftest_runs(serial, kind, started_at) VALUES(?,?,?)
		ON CONFLICT(serial, kind) DO UPDATE SET started_at=excluded.started_at`, serial, kind, at.Unix())
	return err
}

// ---- known disks (for the "disk disappeared" rule)

type SeenDisk struct {
	Serial   string
	Model    string
	Device   string
	LastSeen time.Time
}

func (s *Store) TouchDisk(serial, model, device string, now time.Time) error {
	if serial == "" {
		return nil
	}
	_, err := s.db.Exec(`INSERT INTO disks_seen(serial, model, device, last_seen) VALUES(?,?,?,?)
		ON CONFLICT(serial) DO UPDATE SET model=excluded.model, device=excluded.device, last_seen=excluded.last_seen`,
		serial, model, device, now.Unix())
	return err
}

func (s *Store) SeenDisks() ([]SeenDisk, error) {
	rows, err := s.db.Query(`SELECT serial, model, device, last_seen FROM disks_seen`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []SeenDisk
	for rows.Next() {
		var d SeenDisk
		var ts int64
		if err := rows.Scan(&d.Serial, &d.Model, &d.Device, &ts); err != nil {
			return nil, err
		}
		d.LastSeen = time.Unix(ts, 0)
		out = append(out, d)
	}
	return out, rows.Err()
}

// ForgetDisk drops a disk from the known list (user removed it on purpose).
func (s *Store) ForgetDisk(serial string) error {
	_, err := s.db.Exec(`DELETE FROM disks_seen WHERE serial=?`, serial)
	return err
}