// Package chat orchestrates conversations with the agent gateway, including
// synchronous and streaming chat, scheduled triggers, messages, and memory storage.
package chat

import (
	"encoding/json"
	"strings"
	"time"
)

// Chat kind constants.
const (
	KindDirect = "direct"
	KindGroup  = "group"
	KindThread = "thread"
)

// Participant role constants.
const (
	RoleOwner  = "owner"
	RoleAdmin  = "admin"
	RoleMember = "member"
)

// Chat list access mode constants.
const (
	AccessModeParticipant             = "participant"
	AccessModeChannelIdentityObserved = "channel_identity_observed"
)

// Chat is the first-class conversation container.
type Chat struct {
	ID           string         `json:"id"`
	BotID        string         `json:"bot_id"`
	Kind         string         `json:"kind"`
	ParentChatID string         `json:"parent_chat_id,omitempty"`
	Title        string         `json:"title,omitempty"`
	CreatedBy    string         `json:"created_by"`
	Metadata     map[string]any `json:"metadata,omitempty"`
	CreatedAt    time.Time      `json:"created_at"`
	UpdatedAt    time.Time      `json:"updated_at"`
}

// ChatListItem is a chat entry with access context for list rendering.
type ChatListItem struct {
	ID              string         `json:"id"`
	BotID           string         `json:"bot_id"`
	Kind            string         `json:"kind"`
	ParentChatID    string         `json:"parent_chat_id,omitempty"`
	Title           string         `json:"title,omitempty"`
	CreatedBy       string         `json:"created_by"`
	Metadata        map[string]any `json:"metadata,omitempty"`
	CreatedAt       time.Time      `json:"created_at"`
	UpdatedAt       time.Time      `json:"updated_at"`
	AccessMode      string         `json:"access_mode"`
	ParticipantRole string         `json:"participant_role,omitempty"`
	LastObservedAt  *time.Time     `json:"last_observed_at,omitempty"`
}

// ChatReadAccess is the resolved access context for reading chat content.
type ChatReadAccess struct {
	AccessMode      string
	ParticipantRole string
	LastObservedAt  *time.Time
}

// Participant represents a chat member.
type Participant struct {
	ChatID   string    `json:"chat_id"`
	UserID   string    `json:"user_id"`
	Role     string    `json:"role"`
	JoinedAt time.Time `json:"joined_at"`
}

// Settings holds per-chat configuration.
type Settings struct {
	ChatID              string         `json:"chat_id"`
	EnableChatMemory    bool           `json:"enable_chat_memory"`
	EnablePrivateMemory bool           `json:"enable_private_memory"`
	EnablePublicMemory  bool           `json:"enable_public_memory"`
	ModelID             string         `json:"model_id,omitempty"`
	Metadata            map[string]any `json:"metadata,omitempty"`
}

// Route maps external channel conversations to a chat.
type Route struct {
	ID              string         `json:"id"`
	ChatID          string         `json:"chat_id"`
	BotID           string         `json:"bot_id"`
	Platform        string         `json:"platform"`
	ChannelConfigID string         `json:"channel_config_id,omitempty"`
	ConversationID  string         `json:"conversation_id"`
	ThreadID        string         `json:"thread_id,omitempty"`
	ReplyTarget     string         `json:"reply_target,omitempty"`
	Metadata        map[string]any `json:"metadata,omitempty"`
	CreatedAt       time.Time      `json:"created_at"`
	UpdatedAt       time.Time      `json:"updated_at"`
}

// Message represents a single persisted chat message.
type Message struct {
	ID                      string          `json:"id"`
	ChatID                  string          `json:"chat_id"`
	BotID                   string          `json:"bot_id"`
	RouteID                 string          `json:"route_id,omitempty"`
	SenderChannelIdentityID string          `json:"sender_channel_identity_id,omitempty"`
	SenderUserID            string          `json:"sender_user_id,omitempty"`
	Platform                string          `json:"platform,omitempty"`
	ExternalMessageID       string          `json:"external_message_id,omitempty"`
	Role                    string          `json:"role"`
	Content                 json.RawMessage `json:"content"`
	Metadata                map[string]any  `json:"metadata,omitempty"`
	CreatedAt               time.Time       `json:"created_at"`
}

// CreateChatRequest is the input for creating a chat.
type CreateChatRequest struct {
	Kind         string         `json:"kind"`
	Title        string         `json:"title,omitempty"`
	ParentChatID string         `json:"parent_chat_id,omitempty"`
	Metadata     map[string]any `json:"metadata,omitempty"`
}

// UpdateSettingsRequest is the input for updating chat settings.
type UpdateSettingsRequest struct {
	EnableChatMemory    *bool   `json:"enable_chat_memory,omitempty"`
	EnablePrivateMemory *bool   `json:"enable_private_memory,omitempty"`
	EnablePublicMemory  *bool   `json:"enable_public_memory,omitempty"`
	ModelID             *string `json:"model_id,omitempty"`
}

// ResolveChatResult is returned by ResolveChat.
type ResolveChatResult struct {
	ChatID  string
	RouteID string
	Created bool
}

// ModelMessage is the canonical message format exchanged with the agent gateway.
// Aligned with Vercel AI SDK ModelMessage structure.
type ModelMessage struct {
	Role       string          `json:"role"`
	Content    json.RawMessage `json:"content,omitempty"`
	ToolCalls  []ToolCall      `json:"tool_calls,omitempty"`
	ToolCallID string          `json:"tool_call_id,omitempty"`
	Name       string          `json:"name,omitempty"`
}

// TextContent extracts the plain text from the message content.
// If content is a string, it returns it directly.
// If content is an array of parts, it joins all text-type parts.
func (m ModelMessage) TextContent() string {
	if len(m.Content) == 0 {
		return ""
	}
	var s string
	if err := json.Unmarshal(m.Content, &s); err == nil {
		return s
	}
	var parts []ContentPart
	if err := json.Unmarshal(m.Content, &parts); err == nil {
		texts := make([]string, 0, len(parts))
		for _, p := range parts {
			if strings.TrimSpace(p.Text) != "" {
				texts = append(texts, p.Text)
			}
		}
		return strings.Join(texts, "\n")
	}
	return ""
}

// ContentParts parses the content as an array of ContentPart.
// Returns nil if the content is a plain string or not parseable.
func (m ModelMessage) ContentParts() []ContentPart {
	if len(m.Content) == 0 {
		return nil
	}
	var parts []ContentPart
	if err := json.Unmarshal(m.Content, &parts); err != nil {
		return nil
	}
	return parts
}

// HasContent reports whether the message carries non-empty content or tool calls.
func (m ModelMessage) HasContent() bool {
	if strings.TrimSpace(m.TextContent()) != "" {
		return true
	}
	if len(m.ContentParts()) > 0 {
		return true
	}
	return len(m.ToolCalls) > 0
}

// NewTextContent creates a json.RawMessage from a plain string.
func NewTextContent(text string) json.RawMessage {
	data, _ := json.Marshal(text)
	return data
}

// ContentPart represents one element of a multi-part message content.
type ContentPart struct {
	Type              string         `json:"type"`
	Text              string         `json:"text,omitempty"`
	URL               string         `json:"url,omitempty"`
	Styles            []string       `json:"styles,omitempty"`
	Language          string         `json:"language,omitempty"`
	ChannelIdentityID string         `json:"channel_identity_id,omitempty"`
	Emoji             string         `json:"emoji,omitempty"`
	Metadata          map[string]any `json:"metadata,omitempty"`
}

// HasValue reports whether the content part carries a meaningful value.
func (p ContentPart) HasValue() bool {
	return strings.TrimSpace(p.Text) != "" ||
		strings.TrimSpace(p.URL) != "" ||
		strings.TrimSpace(p.Emoji) != ""
}

// ToolCall represents a function/tool invocation in an assistant message.
type ToolCall struct {
	ID       string           `json:"id,omitempty"`
	Type     string           `json:"type"`
	Function ToolCallFunction `json:"function"`
}

// ToolCallFunction holds the name and serialized arguments of a tool call.
type ToolCallFunction struct {
	Name      string `json:"name"`
	Arguments string `json:"arguments"`
}

// ChatRequest is the input for Chat and StreamChat.
type ChatRequest struct {
	BotID             string `json:"-"`
	ChatID            string `json:"-"`
	Token             string `json:"-"`
	ChannelIdentityID string `json:"-"`
	ContainerID       string `json:"-"`
	DisplayName       string `json:"-"`
	RouteID           string `json:"-"`
	ChatToken         string `json:"-"`
	ExternalMessageID string `json:"-"`

	Query              string         `json:"query"`
	Model              string         `json:"model,omitempty"`
	Provider           string         `json:"provider,omitempty"`
	MaxContextLoadTime int            `json:"max_context_load_time,omitempty"`
	Language           string         `json:"language,omitempty"`
	Channels           []string       `json:"channels,omitempty"`
	CurrentChannel     string         `json:"current_channel,omitempty"`
	Messages           []ModelMessage `json:"messages,omitempty"`
	Skills             []string       `json:"skills,omitempty"`
	AllowedActions     []string       `json:"allowed_actions,omitempty"`
}

// ChatResponse is the output of a non-streaming chat call.
type ChatResponse struct {
	Messages []ModelMessage `json:"messages"`
	Skills   []string       `json:"skills,omitempty"`
	Model    string         `json:"model,omitempty"`
	Provider string         `json:"provider,omitempty"`
}

// StreamChunk is a raw JSON chunk from the streaming response.
type StreamChunk = json.RawMessage

// AssistantOutput holds extracted assistant content for downstream consumers.
type AssistantOutput struct {
	Content string
	Parts   []ContentPart
}