package postgres

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

	"git.gobha.me/xcaliber/chat-switchboard/models"
)

type AttachmentStore struct{}

func NewAttachmentStore() *AttachmentStore { return &AttachmentStore{} }

// ── columns shared across queries ──────────
const attachmentCols = `id, channel_id, user_id, message_id, project_id, filename, content_type,
	size_bytes, storage_key, extracted_text, metadata, created_at`

// scanAttachment scans a row into an Attachment struct.
func scanAttachment(row interface{ Scan(dest ...interface{}) error }) (*models.Attachment, error) {
	var a models.Attachment
	var messageID sql.NullString
	var projectID sql.NullString
	var extractedText sql.NullString
	var metadataJSON []byte

	err := row.Scan(
		&a.ID, &a.ChannelID, &a.UserID, &messageID, &projectID,
		&a.Filename, &a.ContentType, &a.SizeBytes,
		&a.StorageKey, &extractedText, &metadataJSON, &a.CreatedAt,
	)
	if err != nil {
		return nil, err
	}

	a.MessageID = NullableStringPtr(messageID)
	a.ProjectID = NullableStringPtr(projectID)
	if extractedText.Valid {
		a.ExtractedText = &extractedText.String
	}
	if len(metadataJSON) > 0 {
		json.Unmarshal(metadataJSON, &a.Metadata)
	}
	return &a, nil
}

func (s *AttachmentStore) Create(ctx context.Context, a *models.Attachment) error {
	return DB.QueryRowContext(ctx, `
		INSERT INTO attachments (channel_id, user_id, message_id, project_id, filename, content_type,
			size_bytes, storage_key, extracted_text, metadata)
		VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10)
		RETURNING id, created_at`,
		a.ChannelID, a.UserID, models.NullString(a.MessageID),
		models.NullString(a.ProjectID),
		a.Filename, a.ContentType, a.SizeBytes,
		a.StorageKey, models.NullString(a.ExtractedText),
		ToJSON(a.Metadata),
	).Scan(&a.ID, &a.CreatedAt)
}

func (s *AttachmentStore) GetByID(ctx context.Context, id string) (*models.Attachment, error) {
	row := DB.QueryRowContext(ctx, `SELECT `+attachmentCols+` FROM attachments WHERE id = $1`, id)
	return scanAttachment(row)
}

func (s *AttachmentStore) GetByChannel(ctx context.Context, channelID string) ([]models.Attachment, error) {
	rows, err := DB.QueryContext(ctx,
		`SELECT `+attachmentCols+` FROM attachments WHERE channel_id = $1 ORDER BY created_at`, channelID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []models.Attachment
	for rows.Next() {
		a, err := scanAttachment(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, *a)
	}
	return out, rows.Err()
}

func (s *AttachmentStore) GetByMessage(ctx context.Context, messageID string) ([]models.Attachment, error) {
	rows, err := DB.QueryContext(ctx,
		`SELECT `+attachmentCols+` FROM attachments WHERE message_id = $1 ORDER BY created_at`, messageID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []models.Attachment
	for rows.Next() {
		a, err := scanAttachment(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, *a)
	}
	return out, rows.Err()
}

// GetByProject returns all attachments for a project (v0.22.4).
func (s *AttachmentStore) GetByProject(ctx context.Context, projectID string) ([]models.Attachment, error) {
	rows, err := DB.QueryContext(ctx,
		`SELECT `+attachmentCols+` FROM attachments WHERE project_id = $1 ORDER BY created_at`, projectID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []models.Attachment
	for rows.Next() {
		a, err := scanAttachment(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, *a)
	}
	return out, rows.Err()
}

func (s *AttachmentStore) SetMessageID(ctx context.Context, attachmentID, messageID string) error {
	_, err := DB.ExecContext(ctx,
		`UPDATE attachments SET message_id = $1 WHERE id = $2`,
		messageID, attachmentID)
	return err
}

func (s *AttachmentStore) UpdateMetadata(ctx context.Context, id string, metadata map[string]interface{}) error {
	// Merge into existing metadata using jsonb || operator
	metaJSON, err := json.Marshal(metadata)
	if err != nil {
		return err
	}
	_, err = DB.ExecContext(ctx,
		`UPDATE attachments SET metadata = metadata || $1::jsonb WHERE id = $2`,
		metaJSON, id)
	return err
}

func (s *AttachmentStore) SetExtractedText(ctx context.Context, id string, text string) error {
	_, err := DB.ExecContext(ctx,
		`UPDATE attachments SET extracted_text = $1 WHERE id = $2`,
		text, id)
	return err
}

// Delete removes an attachment and returns the deleted row (for storage cleanup).
func (s *AttachmentStore) Delete(ctx context.Context, id string) (*models.Attachment, error) {
	row := DB.QueryRowContext(ctx,
		`DELETE FROM attachments WHERE id = $1
		 RETURNING `+attachmentCols, id)
	return scanAttachment(row)
}

// DeleteByChannel removes all attachments for a channel and returns storage keys.
func (s *AttachmentStore) DeleteByChannel(ctx context.Context, channelID string) ([]string, error) {
	rows, err := DB.QueryContext(ctx,
		`DELETE FROM attachments WHERE channel_id = $1 RETURNING storage_key`, channelID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var keys []string
	for rows.Next() {
		var key string
		if err := rows.Scan(&key); err != nil {
			return keys, err
		}
		keys = append(keys, key)
	}
	return keys, rows.Err()
}

func (s *AttachmentStore) UserUsageBytes(ctx context.Context, userID string) (int64, error) {
	var total sql.NullInt64
	err := DB.QueryRowContext(ctx,
		`SELECT COALESCE(SUM(size_bytes), 0) FROM attachments WHERE user_id = $1`,
		userID).Scan(&total)
	if err != nil {
		return 0, err
	}
	return total.Int64, nil
}

func (s *AttachmentStore) ListOrphans(ctx context.Context, olderThan time.Duration) ([]models.Attachment, error) {
	cutoff := time.Now().Add(-olderThan)
	rows, err := DB.QueryContext(ctx,
		`SELECT `+attachmentCols+` FROM attachments
		 WHERE message_id IS NULL AND created_at < $1
		 ORDER BY created_at`, cutoff)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []models.Attachment
	for rows.Next() {
		a, err := scanAttachment(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, *a)
	}
	return out, rows.Err()
}