export interface ChatOptions {
  signal?: AbortSignal;
}

export interface GatewayTextContentBlock {
  type: 'text';
  text: string;
}

export interface GatewayThinkingContentBlock {
  type: 'thinking';
  thinking: string;
  signature?: string;
}

export interface GatewayToolUseContentBlock {
  type: 'tool_use';
  id: string;
  name: string;
  input?: unknown;
  summary?: string;
}

export interface GatewayToolResultContentBlock {
  type: 'tool_result';
  toolCallId?: string;
  content?: string | GatewayChatContentBlock[];
  result?: unknown;
  summary?: string;
  ok?: boolean;
  error?: unknown;
}

export type GatewayChatContentBlock =
  | GatewayTextContentBlock
  | GatewayThinkingContentBlock
  | GatewayToolUseContentBlock
  | GatewayToolResultContentBlock;

export type GatewayChatMessageRole =
  | 'system'
  | 'user'
  | 'assistant'
  | 'tool'
  | 'toolresult'
  | 'tool_result';

export interface GatewayChatMessage {
  role: GatewayChatMessageRole;
  content: string | GatewayChatContentBlock[];
  name?: string;
  toolCallId?: string;
  metadata?: Record<string, unknown>;
}

export interface GatewayToolDefinition {
  name: string;
  description?: string;
  inputSchema?: unknown;
}

export type GatewayToolChoice =
  | 'auto'
  | 'none'
  | 'required'
  | {
      type: 'tool';
      name: string;
    };

export interface ToolCapableChatOptions extends ChatOptions {
  tools?: GatewayToolDefinition[];
  toolChoice?: GatewayToolChoice;
  metadata?: Record<string, unknown>;
}

export interface ProviderToolCallDelta {
  index?: number;
  id?: string;
  name?: string;
  argumentsDelta?: string;
  raw?: unknown;
}

export interface ProviderCapabilities {
  structuredMessages: boolean;
  toolCalls: boolean;
  toolResults: boolean;
  thinking: boolean;
}

export interface ProviderStreamChunk extends UniversalChunk {
  content?: GatewayChatContentBlock[];
  toolCalls?: ProviderToolCallDelta[];
  finishReason?: string | null;
  raw?: unknown;
}

export const DEFAULT_PROVIDER_CAPABILITIES: ProviderCapabilities = {
  structuredMessages: false,
  toolCalls: false,
  toolResults: false,
  thinking: false,
};

export abstract class BaseProvider {
  getCapabilities(): ProviderCapabilities {
    return DEFAULT_PROVIDER_CAPABILITIES;
  }

  abstract chat(
    messages: GatewayChatMessage[],
    modelName: string,
    options?: ToolCapableChatOptions
  ): Promise<AsyncIterable<ProviderStreamChunk>>
}