package store

import (
	"context"
	"database/sql"
	"fmt"
	"time"
)

// This file holds the Phase 7 delivery helpers (AGENTS.md §4 FR-9, FR-13,
// FR-14): one row in `notifications` per brief per recipient per channel, the
// draft that the Send panel previews, and the summary the dashboard uses to
// show a failed send loudly (FR-12).

// Notification is one brief row: either a draft, or one delivery attempt on one
// channel. It is both the stored summary (FR-10) and the send log (FR-13).
type Notification struct {
	ID int64
	// Scope is the child name, or "combined" for the brief to Jo and Sam.
	Scope string
	// Recipient is the person the brief is for, for example "Harry" or "Jo+Sam".
	Recipient string
	// Channel is "email", "whatsapp", or "" for a draft.
	Channel string
	// Tag is the Apprise tag the delivery used, for example "harry_email".
	Tag string
	// Text is the brief itself (the `summary` column).
	Text string
	// OK reports whether the delivery succeeded.
	OK bool
	// Error is the redacted failure text, empty on success.
	Error string
	// SentAt is when the brief was delivered, or nil for a draft or a failure.
	SentAt *time.Time
	// CreatedAt is when the row was written.
	CreatedAt time.Time
}

// notificationSelect is the shared column list for a notification row.
const notificationSelect = `SELECT id, COALESCE(scope, ''), recipient, COALESCE(channel, ''), COALESCE(tag, ''),
        summary, ok, COALESCE(error, ''), sent_at, created_at FROM notifications`

func scanNotification(r rowScanner) (Notification, error) {
	var n Notification
	var sent sql.NullString
	var created string
	if err := r.Scan(&n.ID, &n.Scope, &n.Recipient, &n.Channel, &n.Tag,
		&n.Text, &n.OK, &n.Error, &sent, &created); err != nil {
		return n, err
	}
	if sent.Valid {
		t := parseTime(sent.String)
		n.SentAt = &t
	}
	n.CreatedAt = parseTime(created)
	return n, nil
}

// RecordNotification writes one brief or one delivery attempt. sent_at is NULL
// while the delivery failed, so a failure can never be read as "delivered".
func (s *Store) RecordNotification(ctx context.Context, n Notification) (int64, error) {
	var sentAt any
	if n.SentAt != nil {
		sentAt = n.SentAt.UTC().Format(time.RFC3339)
	}
	res, err := s.db.ExecContext(ctx,
		`INSERT INTO notifications (scope, recipient, channel, tag, summary, ok, error, sent_at)
		 VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
		n.Scope, n.Recipient, n.Channel, n.Tag, n.Text, n.OK, n.Error, sentAt)
	if err != nil {
		return 0, fmt.Errorf("record notification for %q: %w", n.Recipient, err)
	}
	id, err := res.LastInsertId()
	if err != nil {
		return 0, fmt.Errorf("record notification for %q: %w", n.Recipient, err)
	}
	return id, nil
}

// MarkSummarySent stamps a stored draft as sent and records which channel and
// tag delivered it.
func (s *Store) MarkSummarySent(ctx context.Context, id int64, channel, tag string, ok bool, errText string, at time.Time) error {
	_, err := s.db.ExecContext(ctx,
		`UPDATE notifications SET sent_at = ?, channel = ?, tag = ?, ok = ?, error = ? WHERE id = ?`,
		at.UTC().Format(time.RFC3339), channel, tag, ok, errText, id)
	if err != nil {
		return fmt.Errorf("mark summary %d sent: %w", id, err)
	}
	return nil
}

// RecentNotifications returns the newest brief rows, newest first. limit <= 0
// means twenty.
func (s *Store) RecentNotifications(ctx context.Context, limit int) ([]Notification, error) {
	if limit <= 0 {
		limit = 20
	}
	rows, err := s.db.QueryContext(ctx,
		notificationSelect+` ORDER BY created_at DESC, id DESC LIMIT ?`, limit)
	if err != nil {
		return nil, fmt.Errorf("recent notifications: %w", err)
	}
	defer rows.Close()

	var out []Notification
	for rows.Next() {
		n, err := scanNotification(rows)
		if err != nil {
			return nil, fmt.Errorf("scan notification: %w", err)
		}
		out = append(out, n)
	}
	return out, rows.Err()
}

// NotificationStatus counts the delivery attempts so the dashboard can show a
// failed send loudly (FR-12).
type NotificationStatus struct {
	// Total is every delivery attempt on record.
	Total int
	// Failed is the attempts that did not deliver.
	Failed int
	// Sent is the attempts that delivered.
	Sent int
	// Drafts is the stored briefs that were never sent.
	Drafts int
	// Last is the newest attempt, or nil.
	Last *Notification
}

// EverRun reports whether any delivery has been attempted.
func (st NotificationStatus) EverRun() bool { return st.Total > 0 }

// NotificationSummary reads the delivery log summary.
func (s *Store) NotificationSummary(ctx context.Context) (NotificationStatus, error) {
	var st NotificationStatus
	if err := s.db.QueryRowContext(ctx,
		`SELECT COUNT(*),
		        COALESCE(SUM(CASE WHEN ok = 0 AND channel <> '' THEN 1 ELSE 0 END), 0),
		        COALESCE(SUM(CASE WHEN ok = 1 THEN 1 ELSE 0 END), 0),
		        COALESCE(SUM(CASE WHEN channel = '' THEN 1 ELSE 0 END), 0)
		 FROM notifications`).
		Scan(&st.Total, &st.Failed, &st.Sent, &st.Drafts); err != nil {
		return st, fmt.Errorf("notification summary: %w", err)
	}
	row := s.db.QueryRowContext(ctx, notificationSelect+` ORDER BY id DESC LIMIT 1`)
	n, err := scanNotification(row)
	if err == sql.ErrNoRows {
		return st, nil
	}
	if err != nil {
		return st, fmt.Errorf("last notification: %w", err)
	}
	st.Last = &n
	return st, nil
}

// NotificationByID returns one brief row, or nil when it does not exist.
func (s *Store) NotificationByID(ctx context.Context, id int64) (*Notification, error) {
	row := s.db.QueryRowContext(ctx, notificationSelect+` WHERE id = ?`, id)
	n, err := scanNotification(row)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("notification %d: %w", id, err)
	}
	return &n, nil
}