package llm

import (
	"context"

	"gitea.stevedudenhoeffer.com/steve/go-llm/v2/provider"
)

// Client represents an LLM provider. Create with OpenAI(), Anthropic(), Google().
type Client struct {
	p          provider.Provider
	middleware []Middleware
}

// NewClient creates a Client backed by the given provider.
// Use this to integrate custom provider implementations or for testing.
func NewClient(p provider.Provider) *Client {
	return &Client{p: p}
}

// Model returns a Model for the specified model version.
func (c *Client) Model(modelVersion string) *Model {
	return &Model{
		provider:   c.p,
		model:      modelVersion,
		middleware: c.middleware,
	}
}

// WithMiddleware returns a new Client with additional middleware applied to all models.
func (c *Client) WithMiddleware(mw ...Middleware) *Client {
	c2 := &Client{
		p:          c.p,
		middleware: append(append([]Middleware{}, c.middleware...), mw...),
	}
	return c2
}

// Model represents a specific model from a provider, ready for completions.
type Model struct {
	provider   provider.Provider
	model      string
	middleware []Middleware
}

// Complete sends a non-streaming completion request.
func (m *Model) Complete(ctx context.Context, messages []Message, opts ...RequestOption) (Response, error) {
	cfg := &requestConfig{}
	for _, opt := range opts {
		opt(cfg)
	}

	chain := m.buildChain()
	return chain(ctx, m.model, messages, cfg)
}

// Stream sends a streaming completion request, returning a StreamReader.
func (m *Model) Stream(ctx context.Context, messages []Message, opts ...RequestOption) (*StreamReader, error) {
	cfg := &requestConfig{}
	for _, opt := range opts {
		opt(cfg)
	}

	req := buildProviderRequest(m.model, messages, cfg)
	return newStreamReader(ctx, m.provider, req)
}

// WithMiddleware returns a new Model with additional middleware applied.
func (m *Model) WithMiddleware(mw ...Middleware) *Model {
	return &Model{
		provider:   m.provider,
		model:      m.model,
		middleware: append(append([]Middleware{}, m.middleware...), mw...),
	}
}

func (m *Model) buildChain() CompletionFunc {
	// Base handler that calls the provider
	base := func(ctx context.Context, model string, messages []Message, cfg *requestConfig) (Response, error) {
		req := buildProviderRequest(model, messages, cfg)
		resp, err := m.provider.Complete(ctx, req)
		if err != nil {
			return Response{}, err
		}
		return convertProviderResponse(resp), nil
	}

	// Apply middleware in reverse order (first middleware wraps outermost)
	chain := base
	for i := len(m.middleware) - 1; i >= 0; i-- {
		chain = m.middleware[i](chain)
	}
	return chain
}

func buildProviderRequest(model string, messages []Message, cfg *requestConfig) provider.Request {
	req := provider.Request{
		Model:    model,
		Messages: convertMessages(messages),
	}

	if cfg.temperature != nil {
		req.Temperature = cfg.temperature
	}
	if cfg.maxTokens != nil {
		req.MaxTokens = cfg.maxTokens
	}
	if cfg.topP != nil {
		req.TopP = cfg.topP
	}
	if len(cfg.stop) > 0 {
		req.Stop = cfg.stop
	}

	if cfg.tools != nil {
		for _, tool := range cfg.tools.AllTools() {
			req.Tools = append(req.Tools, provider.ToolDef{
				Name:        tool.Name,
				Description: tool.Description,
				Schema:      tool.Schema,
			})
		}
	}

	return req
}

func convertMessages(msgs []Message) []provider.Message {
	out := make([]provider.Message, len(msgs))
	for i, m := range msgs {
		pm := provider.Message{
			Role:       string(m.Role),
			Content:    m.Content.Text,
			ToolCallID: m.ToolCallID,
		}
		for _, img := range m.Content.Images {
			pm.Images = append(pm.Images, provider.Image{
				URL:         img.URL,
				Base64:      img.Base64,
				ContentType: img.ContentType,
			})
		}
		for _, tc := range m.ToolCalls {
			pm.ToolCalls = append(pm.ToolCalls, provider.ToolCall{
				ID:        tc.ID,
				Name:      tc.Name,
				Arguments: tc.Arguments,
			})
		}
		out[i] = pm
	}
	return out
}

func convertProviderResponse(resp provider.Response) Response {
	r := Response{
		Text: resp.Text,
	}

	for _, tc := range resp.ToolCalls {
		r.ToolCalls = append(r.ToolCalls, ToolCall{
			ID:        tc.ID,
			Name:      tc.Name,
			Arguments: tc.Arguments,
		})
	}

	if resp.Usage != nil {
		r.Usage = &Usage{
			InputTokens:  resp.Usage.InputTokens,
			OutputTokens: resp.Usage.OutputTokens,
			TotalTokens:  resp.Usage.TotalTokens,
		}
	}

	// Build the assistant message for conversation history
	r.message = Message{
		Role:      RoleAssistant,
		Content:   Content{Text: resp.Text},
		ToolCalls: r.ToolCalls,
	}

	return r
}

// --- Provider constructors ---
// These are defined here and delegate to provider-specific packages.
// They are set up via init() in the provider packages, or defined directly.

// ClientOption configures a client.
type ClientOption func(*clientConfig)

type clientConfig struct {
	baseURL string
}

// WithBaseURL overrides the API base URL.
func WithBaseURL(url string) ClientOption {
	return func(c *clientConfig) { c.baseURL = url }
}