package provider

import (
	"context"

	"github.com/gochat/gochat/internal/model/channel"
)

// ChannelProvider defines the interface that every channel type must implement.
// This mirrors Chatwoot's channel provider pattern where each channel (web_widget,
// facebook, twitter, etc.) handles its own message processing, webhook handling,
// and contact identification.
type ChannelProvider interface {
	// Name returns the channel type identifier (e.g., "web_widget", "facebook").
	Name() string

	// CreateChannel persists a new channel of this type with the given params.
	CreateChannel(ctx context.Context, accountID uint, params map[string]interface{}) (channel.Channelable, error)

	// UpdateChannel modifies an existing channel's configuration.
	UpdateChannel(ctx context.Context, channelID uint, params map[string]interface{}) (channel.Channelable, error)

	// DeleteChannel removes a channel.
	DeleteChannel(ctx context.Context, channelID uint) error

	// HandleWebhook processes incoming webhook events from the channel source.
	HandleWebhook(ctx context.Context, payload map[string]interface{}) error

	// ProcessIncomingMessage transforms a raw channel payload into a gochat Message.
	ProcessIncomingMessage(ctx context.Context, inboxID uint, contactID uint, payload map[string]interface{}) (*IncomingMessageResult, error)

	// ProcessOutgoingMessage sends a message back through the channel.
	ProcessOutgoingMessage(ctx context.Context, conversationID uint, messageID uint, content string) error

	// ValidateConfig checks that the channel-specific config params are valid.
	ValidateConfig(params map[string]interface{}) error
}

// IncomingMessageResult holds the processed result of an incoming channel message.
type IncomingMessageResult struct {
	Content     string            `json:"content"`
	ContentType string            `json:"content_type"`
	SourceID    string            `json:"source_id"`
	Extras      map[string]interface{} `json:"extras,omitempty"`
}

// ChannelRegistry holds all registered channel providers.
type ChannelRegistry struct {
	providers map[string]ChannelProvider
}

// NewChannelRegistry creates an empty registry.
func NewChannelRegistry() *ChannelRegistry {
	return &ChannelRegistry{
		providers: make(map[string]ChannelProvider),
	}
}

// Register adds a channel provider to the registry.
func (r *ChannelRegistry) Register(provider ChannelProvider) {
	r.providers[provider.Name()] = provider
}

// Get returns a channel provider by name, or nil if not found.
func (r *ChannelRegistry) Get(name string) ChannelProvider {
	return r.providers[name]
}

// List returns all registered provider names.
func (r *ChannelRegistry) List() []string {
	names := make([]string, 0, len(r.providers))
	for name := range r.providers {
		names = append(names, name)
	}
	return names
}