// Package models defines the data models used by the chat application.
// All model structs embed Base, which provides database access for
// relation-fetching methods directly on model instances.
package models

import (
	"context"
	"database/sql"
)

// DB is the interface that models use to query the database.
// This avoids a circular import with the db package.
type DB interface {
	GetDB() *sql.DB
}

// UserLookup provides user lookup by ID without circular imports.
type UserLookup interface {
	GetUserByID(ctx context.Context, id string) (*User, error)
}

// ChannelLookup provides channel lookup by ID without circular imports.
type ChannelLookup interface {
	GetChannelByID(ctx context.Context, id string) (*Channel, error)
}

// Base is embedded in all model structs to provide database access.
type Base struct {
	db DB
}

// SetDB injects the database reference into a model.
func (b *Base) SetDB(d DB) {
	b.db = d
}

// GetDB returns the database interface for use in model methods.
func (b *Base) GetDB() *sql.DB {
	return b.db.GetDB()
}

// LookupUser looks up a user by ID if the database supports it.
func (b *Base) LookupUser(ctx context.Context, id string) (*User, error) {
	ul, ok := b.db.(UserLookup)
	if !ok {
		return nil, ErrUserLookupNotAvailable
	}

	return ul.GetUserByID(ctx, id)
}

// LookupChannel looks up a channel by ID if the database supports it.
func (b *Base) LookupChannel(ctx context.Context, id string) (*Channel, error) {
	cl, ok := b.db.(ChannelLookup)
	if !ok {
		return nil, ErrChannelLookupNotAvailable
	}

	return cl.GetChannelByID(ctx, id)
}