// Package feedback owns user feedback: the flat list of messages a registered
// player sends to the operators (each with an optional single attachment), the
// anti-spam "one pending message at a time" gate, and the operator's inline reply
// delivered back to the player's app. It is modelled on the admin chat-moderation
// surface (internal/social/adminchat.go) and uses raw SQL throughout for the
// attachment bytea, the COALESCE-based "set once" stamps, and the reply-visibility
// window.
package feedback

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

	"github.com/google/uuid"

	"scrabble/backend/internal/account"
)

// ErrNotFound is returned when no feedback message matches the lookup.
var ErrNotFound = errors.New("feedback: not found")

// Store is the Postgres-backed query surface for feedback_messages.
type Store struct {
	db *sql.DB
}

// NewStore constructs a Store wrapping db.
func NewStore(db *sql.DB) *Store {
	return &Store{db: db}
}

// Insert stores one feedback message from accountID and returns its id. attachment
// is the raw file bytes (nil for none); attachmentName, ip and a non-default
// channel are stored as given. lang (interface language), version (client app build) and
// browserTZ (the client's detected "±HH:MM" UTC offset) are snapshots taken now, so the operator
// later sees the state at submit time. created_at defaults to now() in the database.
func (s *Store) Insert(ctx context.Context, accountID uuid.UUID, body string, attachment []byte, attachmentName, channel, lang, version, browserTZ string, ip *string) (uuid.UUID, error) {
	id, err := uuid.NewV7()
	if err != nil {
		return uuid.Nil, fmt.Errorf("feedback: new message id: %w", err)
	}
	var att []byte // a nil []byte binds as bytea NULL
	if len(attachment) > 0 {
		att = attachment
	}
	if _, err := s.db.ExecContext(ctx,
		`INSERT INTO backend.feedback_messages
		   (message_id, account_id, body, attachment, attachment_name, channel, lang, app_version, browser_tz, sender_ip)
		 VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)`,
		id, accountID, body, att, nullStr(attachmentName), channel, nullStr(lang), nullStr(version), nullStr(browserTZ), ip); err != nil {
		return uuid.Nil, fmt.Errorf("feedback: insert: %w", err)
	}
	return id, nil
}

// nullStr maps an empty string to a NULL text bind, else the value.
func nullStr(s string) *string {
	if s == "" {
		return nil
	}
	return &s
}

// HasUnread reports whether the account has any message the operator has not yet
// dealt with (read_at IS NULL) — the anti-spam gate's condition.
func (s *Store) HasUnread(ctx context.Context, accountID uuid.UUID) (bool, error) {
	var ok bool
	if err := s.db.QueryRowContext(ctx,
		`SELECT EXISTS (SELECT 1 FROM backend.feedback_messages WHERE account_id = $1 AND read_at IS NULL)`,
		accountID).Scan(&ok); err != nil {
		return false, fmt.Errorf("feedback: has-unread %s: %w", accountID, err)
	}
	return ok, nil
}

// HasUnreadReply reports whether the account has an operator reply not yet
// delivered to its app (reply_read_at IS NULL) — the badge's condition.
func (s *Store) HasUnreadReply(ctx context.Context, accountID uuid.UUID) (bool, error) {
	var ok bool
	if err := s.db.QueryRowContext(ctx,
		`SELECT EXISTS (SELECT 1 FROM backend.feedback_messages
		   WHERE account_id = $1 AND reply_body IS NOT NULL AND reply_read_at IS NULL)`,
		accountID).Scan(&ok); err != nil {
		return false, fmt.Errorf("feedback: has-unread-reply %s: %w", accountID, err)
	}
	return ok, nil
}

// VisibleReply is the operator reply shown back to the player: the reply on their
// most recent replied message still inside the visibility window.
type VisibleReply struct {
	Body      string
	RepliedAt time.Time
}

// LatestVisibleReply returns the reply on the account's **most recent** message, if
// that message carries one still visible to the player — not yet delivered, or
// delivered after cutoff (one week ago). Binding it to the single latest message
// means that the moment the player sends a newer message the previous reply stops
// showing (the new message has no reply yet). Reports false when there is none.
func (s *Store) LatestVisibleReply(ctx context.Context, accountID uuid.UUID, cutoff time.Time) (VisibleReply, bool, error) {
	var vr VisibleReply
	var repliedAt sql.NullTime
	err := s.db.QueryRowContext(ctx,
		`SELECT COALESCE(reply_body, ''), replied_at FROM (
			SELECT reply_body, replied_at, reply_read_at FROM backend.feedback_messages
			WHERE account_id = $1 ORDER BY created_at DESC LIMIT 1
		) latest
		WHERE reply_body IS NOT NULL AND (reply_read_at IS NULL OR reply_read_at > $2)`,
		accountID, cutoff).Scan(&vr.Body, &repliedAt)
	if errors.Is(err, sql.ErrNoRows) {
		return VisibleReply{}, false, nil
	}
	if err != nil {
		return VisibleReply{}, false, fmt.Errorf("feedback: latest visible reply %s: %w", accountID, err)
	}
	if repliedAt.Valid {
		vr.RepliedAt = repliedAt.Time
	}
	return vr, true, nil
}

// MarkRepliesDelivered stamps reply_read_at on every not-yet-delivered reply of the
// account (delivery counts as read), clearing the badge when the player opens the
// feedback screen.
func (s *Store) MarkRepliesDelivered(ctx context.Context, accountID uuid.UUID, at time.Time) error {
	if _, err := s.db.ExecContext(ctx,
		`UPDATE backend.feedback_messages SET reply_read_at = $2
		 WHERE account_id = $1 AND reply_body IS NOT NULL AND reply_read_at IS NULL`,
		accountID, at); err != nil {
		return fmt.Errorf("feedback: mark replies delivered %s: %w", accountID, err)
	}
	return nil
}

// MarkRead stamps read_at the first time, marking the message dealt-with without any
// other action; a re-mark keeps the original time.
func (s *Store) MarkRead(ctx context.Context, id uuid.UUID, at time.Time) error {
	if _, err := s.db.ExecContext(ctx,
		`UPDATE backend.feedback_messages SET read_at = COALESCE(read_at, $2) WHERE message_id = $1`,
		id, at); err != nil {
		return fmt.Errorf("feedback: mark read %s: %w", id, err)
	}
	return nil
}

// Reply sets (or replaces) the operator reply on a message, marks it read, and
// resets its delivery so the player is notified again. Returns the message's
// account_id for the live notification, or ErrNotFound.
func (s *Store) Reply(ctx context.Context, id uuid.UUID, body string, at time.Time) (uuid.UUID, error) {
	var accountID uuid.UUID
	err := s.db.QueryRowContext(ctx,
		`UPDATE backend.feedback_messages
		   SET reply_body = $2, replied_at = $3, reply_read_at = NULL, read_at = COALESCE(read_at, $3)
		 WHERE message_id = $1
		 RETURNING account_id`,
		id, body, at).Scan(&accountID)
	if errors.Is(err, sql.ErrNoRows) {
		return uuid.Nil, ErrNotFound
	}
	if err != nil {
		return uuid.Nil, fmt.Errorf("feedback: reply %s: %w", id, err)
	}
	return accountID, nil
}

// Archive files a handled message away and marks it read.
func (s *Store) Archive(ctx context.Context, id uuid.UUID, at time.Time) error {
	if _, err := s.db.ExecContext(ctx,
		`UPDATE backend.feedback_messages
		   SET archived_at = COALESCE(archived_at, $2), read_at = COALESCE(read_at, $2)
		 WHERE message_id = $1`,
		id, at); err != nil {
		return fmt.Errorf("feedback: archive %s: %w", id, err)
	}
	return nil
}

// Delete physically removes a message (with its attachment).
func (s *Store) Delete(ctx context.Context, id uuid.UUID) error {
	if _, err := s.db.ExecContext(ctx,
		`DELETE FROM backend.feedback_messages WHERE message_id = $1`, id); err != nil {
		return fmt.Errorf("feedback: delete %s: %w", id, err)
	}
	return nil
}

// DeleteAllByAccount physically removes every message of an account.
func (s *Store) DeleteAllByAccount(ctx context.Context, accountID uuid.UUID) error {
	if _, err := s.db.ExecContext(ctx,
		`DELETE FROM backend.feedback_messages WHERE account_id = $1`, accountID); err != nil {
		return fmt.Errorf("feedback: delete all %s: %w", accountID, err)
	}
	return nil
}

// Attachment returns a message's stored file name and bytes, reporting false when
// the message has no attachment or does not exist.
func (s *Store) Attachment(ctx context.Context, id uuid.UUID) (string, []byte, bool, error) {
	var name string
	var data []byte
	err := s.db.QueryRowContext(ctx,
		`SELECT COALESCE(attachment_name, ''), attachment FROM backend.feedback_messages WHERE message_id = $1`,
		id).Scan(&name, &data)
	if errors.Is(err, sql.ErrNoRows) {
		return "", nil, false, nil
	}
	if err != nil {
		return "", nil, false, fmt.Errorf("feedback: attachment %s: %w", id, err)
	}
	if data == nil {
		return "", nil, false, nil
	}
	return name, data, true, nil
}

// AdminMessage is one feedback message in the operator console detail view: the
// message with its sender's resolved display name and source. The attachment bytes
// are not loaded here (served separately); only their presence and name are.
type AdminMessage struct {
	ID         uuid.UUID
	AccountID  uuid.UUID
	SenderName string
	Source     string
	Body       string
	Channel    string
	// Lang is the sender's interface language, snapshotted at submit time.
	Lang string
	// Version is the client app build the report was sent from, snapshotted at submit time.
	Version string
	// BrowserTZ is the client's detected "±HH:MM" UTC offset at submit time, snapshotted so the
	// filed time can be shown in the sender's browser-local zone even before they save a profile.
	BrowserTZ string
	// TimeZone is the sender account's stored zone ("±HH:MM" offset, IANA name, or ""), for
	// rendering CreatedAt in the sender's own configured time alongside UTC.
	TimeZone       string
	SenderIP       string
	HasAttachment  bool
	AttachmentName string
	Read           bool
	Archived       bool
	Replied        bool
	ReplyBody      string
	RepliedAt      time.Time
	CreatedAt      time.Time
}

// AdminRow is one feedback message in the console list (a lighter projection).
type AdminRow struct {
	ID            uuid.UUID
	AccountID     uuid.UUID
	SenderName    string
	Source        string
	Channel       string
	HasAttachment bool
	Read          bool
	Replied       bool
	Archived      bool
	CreatedAt     time.Time
}

// AdminFilter narrows the console feedback list. Status is one of "unread"
// (default), "read" or "archived". NameMask/ExtMask are glob masks
// (account.LikePattern) on the sender's display name / any identity's external id;
// AccountID, when set, restricts to one account (the per-user link from /users).
type AdminFilter struct {
	Status    string
	NameMask  string
	ExtMask   string
	AccountID uuid.UUID
}

// feedbackSource projects a sender's source: guest, robot, or its oldest identity
// kind ("—" when it has none). Mirrors social.adminMessageSource.
const feedbackSource = `CASE
	WHEN a.is_guest THEN 'guest'
	WHEN EXISTS (SELECT 1 FROM backend.identities i WHERE i.account_id = a.account_id AND i.kind = 'robot') THEN 'robot'
	ELSE COALESCE((SELECT i2.kind FROM backend.identities i2 WHERE i2.account_id = a.account_id ORDER BY i2.created_at ASC LIMIT 1), '—')
END`

// adminWhere builds the shared WHERE clause and its positional args (from $1).
func adminWhere(f AdminFilter) (string, []any) {
	var where string
	switch f.Status {
	case "archived":
		where = `m.archived_at IS NOT NULL`
	case "read":
		where = `m.read_at IS NOT NULL AND m.archived_at IS NULL`
	default: // unread
		where = `m.read_at IS NULL AND m.archived_at IS NULL`
	}
	var args []any
	if f.AccountID != uuid.Nil {
		args = append(args, f.AccountID)
		where += fmt.Sprintf(` AND m.account_id = $%d`, len(args))
	}
	if name := account.LikePattern(f.NameMask); name != "" {
		args = append(args, name)
		where += fmt.Sprintf(` AND a.display_name ILIKE $%d ESCAPE '\'`, len(args))
	}
	if ext := account.LikePattern(f.ExtMask); ext != "" {
		args = append(args, ext)
		where += fmt.Sprintf(` AND EXISTS (SELECT 1 FROM backend.identities ie WHERE ie.account_id = a.account_id AND ie.external_id ILIKE $%d ESCAPE '\')`, len(args))
	}
	return where, args
}

// AdminList returns the filtered console feedback list, newest first, paginated.
func (s *Store) AdminList(ctx context.Context, f AdminFilter, limit, offset int) ([]AdminRow, error) {
	where, args := adminWhere(f)
	q := `SELECT m.message_id, m.account_id, a.display_name, ` + feedbackSource + ` AS source, m.channel,
		(m.attachment IS NOT NULL), (m.read_at IS NOT NULL), (m.reply_body IS NOT NULL), (m.archived_at IS NOT NULL), m.created_at
	FROM backend.feedback_messages m
	JOIN backend.accounts a ON a.account_id = m.account_id
	WHERE ` + where +
		fmt.Sprintf(` ORDER BY m.created_at DESC LIMIT $%d OFFSET $%d`, len(args)+1, len(args)+2)
	args = append(args, limit, offset)
	rows, err := s.db.QueryContext(ctx, q, args...)
	if err != nil {
		return nil, fmt.Errorf("feedback: admin list: %w", err)
	}
	defer rows.Close()
	var out []AdminRow
	for rows.Next() {
		var r AdminRow
		if err := rows.Scan(&r.ID, &r.AccountID, &r.SenderName, &r.Source, &r.Channel,
			&r.HasAttachment, &r.Read, &r.Replied, &r.Archived, &r.CreatedAt); err != nil {
			return nil, fmt.Errorf("feedback: scan admin row: %w", err)
		}
		out = append(out, r)
	}
	return out, rows.Err()
}

// AdminCount counts the filtered console feedback list, for the pager.
func (s *Store) AdminCount(ctx context.Context, f AdminFilter) (int, error) {
	where, args := adminWhere(f)
	var n int
	q := `SELECT COUNT(*) FROM backend.feedback_messages m JOIN backend.accounts a ON a.account_id = m.account_id WHERE ` + where
	if err := s.db.QueryRowContext(ctx, q, args...).Scan(&n); err != nil {
		return 0, fmt.Errorf("feedback: admin count: %w", err)
	}
	return n, nil
}

// AdminGet loads one message for the console detail view, or ErrNotFound.
func (s *Store) AdminGet(ctx context.Context, id uuid.UUID) (AdminMessage, error) {
	var m AdminMessage
	var repliedAt sql.NullTime
	q := `SELECT m.message_id, m.account_id, a.display_name, ` + feedbackSource + ` AS source, m.body, m.channel,
		COALESCE(m.lang, ''), COALESCE(m.app_version, ''), COALESCE(m.browser_tz, ''), a.time_zone,
		COALESCE(m.sender_ip, ''), (m.attachment IS NOT NULL), COALESCE(m.attachment_name, ''),
		(m.read_at IS NOT NULL), (m.archived_at IS NOT NULL), (m.reply_body IS NOT NULL),
		COALESCE(m.reply_body, ''), m.replied_at, m.created_at
	FROM backend.feedback_messages m
	JOIN backend.accounts a ON a.account_id = m.account_id
	WHERE m.message_id = $1`
	err := s.db.QueryRowContext(ctx, q, id).Scan(
		&m.ID, &m.AccountID, &m.SenderName, &m.Source, &m.Body, &m.Channel,
		&m.Lang, &m.Version, &m.BrowserTZ, &m.TimeZone,
		&m.SenderIP, &m.HasAttachment, &m.AttachmentName,
		&m.Read, &m.Archived, &m.Replied, &m.ReplyBody, &repliedAt, &m.CreatedAt)
	if errors.Is(err, sql.ErrNoRows) {
		return AdminMessage{}, ErrNotFound
	}
	if err != nil {
		return AdminMessage{}, fmt.Errorf("feedback: admin get %s: %w", id, err)
	}
	if repliedAt.Valid {
		m.RepliedAt = repliedAt.Time
	}
	return m, nil
}

// CountUnread counts the active (unread, not archived) feedback queue, for the
// console dashboard.
func (s *Store) CountUnread(ctx context.Context) (int, error) {
	var n int
	if err := s.db.QueryRowContext(ctx,
		`SELECT COUNT(*) FROM backend.feedback_messages WHERE read_at IS NULL AND archived_at IS NULL`,
	).Scan(&n); err != nil {
		return 0, fmt.Errorf("feedback: count unread: %w", err)
	}
	return n, nil
}