// PicoClaw - Ultra-lightweight personal AI agent
// License: MIT
//
// Copyright (c) 2026 PicoClaw contributors

package providers

import (
	"fmt"
	"strings"

	"github.com/sipeed/picoclaw/pkg/config"
	anthropicmessages "github.com/sipeed/picoclaw/pkg/providers/anthropic_messages"
	"github.com/sipeed/picoclaw/pkg/providers/azure"
)

// createClaudeAuthProvider creates a Claude provider using OAuth credentials from auth store.
func createClaudeAuthProvider() (LLMProvider, error) {
	cred, err := getCredential("anthropic")
	if err != nil {
		return nil, fmt.Errorf("loading auth credentials: %w", err)
	}
	if cred == nil {
		return nil, fmt.Errorf("no credentials for anthropic. Run: picoclaw auth login --provider anthropic")
	}
	return NewClaudeProviderWithTokenSource(cred.AccessToken, createClaudeTokenSource()), nil
}

// createCodexAuthProvider creates a Codex provider using OAuth credentials from auth store.
func createCodexAuthProvider() (LLMProvider, error) {
	cred, err := getCredential("openai")
	if err != nil {
		return nil, fmt.Errorf("loading auth credentials: %w", err)
	}
	if cred == nil {
		return nil, fmt.Errorf("no credentials for openai. Run: picoclaw auth login --provider openai")
	}
	return NewCodexProviderWithTokenSource(cred.AccessToken, cred.AccountID, createCodexTokenSource()), nil
}

// ExtractProtocol extracts the protocol prefix and model identifier from a model string.
// If no prefix is specified, it defaults to "openai".
// Examples:
//   - "openai/gpt-4o" -> ("openai", "gpt-4o")
//   - "anthropic/claude-sonnet-4.6" -> ("anthropic", "claude-sonnet-4.6")
//   - "gpt-4o" -> ("openai", "gpt-4o")  // default protocol
func ExtractProtocol(model string) (protocol, modelID string) {
	model = strings.TrimSpace(model)
	protocol, modelID, found := strings.Cut(model, "/")
	if !found {
		return "openai", model
	}
	return protocol, modelID
}

// CreateProviderFromConfig creates a provider based on the ModelConfig.
// It uses the protocol prefix in the Model field to determine which provider to create.
// Supported protocols: openai, litellm, novita, anthropic, anthropic-messages,
// antigravity, claude-cli, codex-cli, github-copilot
// Returns the provider, the model ID (without protocol prefix), and any error.
func CreateProviderFromConfig(cfg *config.ModelConfig) (LLMProvider, string, error) {
	if cfg == nil {
		return nil, "", fmt.Errorf("config is nil")
	}

	if cfg.Model == "" {
		return nil, "", fmt.Errorf("model is required")
	}

	protocol, modelID := ExtractProtocol(cfg.Model)

	switch protocol {
	case "openai":
		// OpenAI with OAuth/token auth (Codex-style)
		if cfg.AuthMethod == "oauth" || cfg.AuthMethod == "token" {
			provider, err := createCodexAuthProvider()
			if err != nil {
				return nil, "", err
			}
			return provider, modelID, nil
		}
		// OpenAI with API key
		if cfg.APIKey == "" && cfg.APIBase == "" {
			return nil, "", fmt.Errorf("api_key or api_base is required for HTTP-based protocol %q", protocol)
		}
		apiBase := cfg.APIBase
		if apiBase == "" {
			apiBase = getDefaultAPIBase(protocol)
		}
		return NewHTTPProviderWithMaxTokensFieldAndRequestTimeout(
			cfg.APIKey,
			apiBase,
			cfg.Proxy,
			cfg.MaxTokensField,
			cfg.RequestTimeout,
		), modelID, nil

	case "azure", "azure-openai":
		// Azure OpenAI uses deployment-based URLs, api-key header auth,
		// and always sends max_completion_tokens.
		if cfg.APIKey == "" {
			return nil, "", fmt.Errorf("api_key is required for azure protocol")
		}
		if cfg.APIBase == "" {
			return nil, "", fmt.Errorf(
				"api_base is required for azure protocol (e.g., https://your-resource.openai.azure.com)",
			)
		}
		return azure.NewProviderWithTimeout(
			cfg.APIKey,
			cfg.APIBase,
			cfg.Proxy,
			cfg.RequestTimeout,
		), modelID, nil

	case "litellm", "openrouter", "groq", "zhipu", "gemini", "nvidia",
		"ollama", "moonshot", "shengsuanyun", "deepseek", "cerebras",
		"vivgrid", "volcengine", "vllm", "qwen", "mistral", "avian",
		"minimax", "longcat", "modelscope", "novita":
		// All other OpenAI-compatible HTTP providers
		if cfg.APIKey == "" && cfg.APIBase == "" {
			return nil, "", fmt.Errorf("api_key or api_base is required for HTTP-based protocol %q", protocol)
		}
		apiBase := cfg.APIBase
		if apiBase == "" {
			apiBase = getDefaultAPIBase(protocol)
		}
		return NewHTTPProviderWithMaxTokensFieldAndRequestTimeout(
			cfg.APIKey,
			apiBase,
			cfg.Proxy,
			cfg.MaxTokensField,
			cfg.RequestTimeout,
		), modelID, nil

	case "anthropic":
		if cfg.AuthMethod == "oauth" || cfg.AuthMethod == "token" {
			// Use OAuth credentials from auth store
			provider, err := createClaudeAuthProvider()
			if err != nil {
				return nil, "", err
			}
			return provider, modelID, nil
		}
		// Use API key with HTTP API
		apiBase := cfg.APIBase
		if apiBase == "" {
			apiBase = "https://api.anthropic.com/v1"
		}
		if cfg.APIKey == "" {
			return nil, "", fmt.Errorf("api_key is required for anthropic protocol (model: %s)", cfg.Model)
		}
		return NewHTTPProviderWithMaxTokensFieldAndRequestTimeout(
			cfg.APIKey,
			apiBase,
			cfg.Proxy,
			cfg.MaxTokensField,
			cfg.RequestTimeout,
		), modelID, nil

	case "anthropic-messages":
		// Anthropic Messages API with native format (HTTP-based, no SDK)
		apiBase := cfg.APIBase
		if apiBase == "" {
			apiBase = "https://api.anthropic.com/v1"
		}
		if cfg.APIKey == "" {
			return nil, "", fmt.Errorf("api_key is required for anthropic-messages protocol (model: %s)", cfg.Model)
		}
		return anthropicmessages.NewProviderWithTimeout(
			cfg.APIKey,
			apiBase,
			cfg.RequestTimeout,
		), modelID, nil

	case "antigravity":
		return NewAntigravityProvider(), modelID, nil

	case "claude-cli", "claudecli":
		workspace := cfg.Workspace
		if workspace == "" {
			workspace = "."
		}
		return NewClaudeCliProvider(workspace), modelID, nil

	case "codex-cli", "codexcli":
		workspace := cfg.Workspace
		if workspace == "" {
			workspace = "."
		}
		return NewCodexCliProvider(workspace), modelID, nil

	case "github-copilot", "copilot":
		apiBase := cfg.APIBase
		if apiBase == "" {
			apiBase = "localhost:4321"
		}
		connectMode := cfg.ConnectMode
		if connectMode == "" {
			connectMode = "grpc"
		}
		provider, err := NewGitHubCopilotProvider(apiBase, connectMode, modelID)
		if err != nil {
			return nil, "", err
		}
		return provider, modelID, nil

	default:
		return nil, "", fmt.Errorf("unknown protocol %q in model %q", protocol, cfg.Model)
	}
}

// getDefaultAPIBase returns the default API base URL for a given protocol.
func getDefaultAPIBase(protocol string) string {
	switch protocol {
	case "openai":
		return "https://api.openai.com/v1"
	case "openrouter":
		return "https://openrouter.ai/api/v1"
	case "litellm":
		return "http://localhost:4000/v1"
	case "novita":
		return "https://api.novita.ai/openai"
	case "groq":
		return "https://api.groq.com/openai/v1"
	case "zhipu":
		return "https://open.bigmodel.cn/api/paas/v4"
	case "gemini":
		return "https://generativelanguage.googleapis.com/v1beta"
	case "nvidia":
		return "https://integrate.api.nvidia.com/v1"
	case "ollama":
		return "http://localhost:11434/v1"
	case "moonshot":
		return "https://api.moonshot.cn/v1"
	case "shengsuanyun":
		return "https://router.shengsuanyun.com/api/v1"
	case "deepseek":
		return "https://api.deepseek.com/v1"
	case "cerebras":
		return "https://api.cerebras.ai/v1"
	case "vivgrid":
		return "https://api.vivgrid.com/v1"
	case "volcengine":
		return "https://ark.cn-beijing.volces.com/api/v3"
	case "qwen":
		return "https://dashscope.aliyuncs.com/compatible-mode/v1"
	case "vllm":
		return "http://localhost:8000/v1"
	case "mistral":
		return "https://api.mistral.ai/v1"
	case "avian":
		return "https://api.avian.io/v1"
	case "minimax":
		return "https://api.minimaxi.com/v1"
	case "longcat":
		return "https://api.longcat.chat/openai"
	case "modelscope":
		return "https://api-inference.modelscope.cn/v1"
	default:
		return ""
	}
}