package modelprovider

import (
	"context"
	"errors"
	"time"
)

type Client struct {
	provider     Provider
	defaultModel string
}

func NewClient(p Provider, defaultModel string) *Client {
	return &Client{provider: p, defaultModel: defaultModel}
}

// Chat 对话接口
func (c *Client) Chat(ctx context.Context, req ChatRequest) (*ChatResponse, error) {
	if len(req.Messages) == 0 {
		return nil, errors.New("empty messages")
	}
	if req.Model == "" {
		req.Model = c.defaultModel
	}
	resp, err := c.provider.InvokeCompletion(ctx, &req)
	if err != nil {
		return nil, err
	}
	if resp != nil {
		if resp.Meta.Vendor == "" {
			resp.Meta.Vendor = c.provider.Capabilities().Vendor
		}
		if resp.Meta.CreatedAt.IsZero() {
			resp.Meta.CreatedAt = time.Now()
		}
		if resp.Model == "" {
			resp.Model = req.Model
		}
	}
	return resp, nil
}

// StreamChat 流式问答接口
func (c *Client) StreamChat(ctx context.Context, req ChatRequest, handler StreamChatCallback) error {
	if len(req.Messages) == 0 {
		return errors.New("empty messages")
	}
	if req.Model == "" {
		req.Model = c.defaultModel
	}
	if !c.provider.Capabilities().SupportsStreaming {
		return errors.New("provider does not support streaming")
	}
	return c.provider.StreamCompletion(ctx, &req, handler)
}