// Summary: Hexai LSP runner; configures logging, loads config, builds the LLM client,
// and constructs/runs the LSP server (with injectable factory for tests).
package hexailsp

import (
	"io"
	"log"
	"os"
	"strings"

	"hexai/internal/appconfig"
	"hexai/internal/llm"
	"hexai/internal/logging"
	"hexai/internal/lsp"
)

// ServerRunner is the minimal interface satisfied by lsp.Server.
type ServerRunner interface{ Run() error }

// ServerFactory creates a ServerRunner. Default uses lsp.NewServer.
type ServerFactory func(r io.Reader, w io.Writer, logger *log.Logger, opts lsp.ServerOptions) ServerRunner

// Run configures logging, loads config, builds the LLM client and runs the LSP server.
// It is thin and delegates to RunWithFactory for testability.
func Run(logPath string, stdin io.Reader, stdout io.Writer, stderr io.Writer) error {
	logger := log.New(stderr, "hexai-lsp ", log.LstdFlags|log.Lmsgprefix)
	if strings.TrimSpace(logPath) != "" {
		f, err := os.OpenFile(logPath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
		if err != nil {
			logger.Fatalf("failed to open log file: %v", err)
		}
		defer f.Close()
		logger.SetOutput(f)
	}
	logging.Bind(logger)
	cfg := appconfig.Load(logger)
	return RunWithFactory(logPath, stdin, stdout, logger, cfg, nil, nil)
}

// RunWithFactory is the testable entrypoint. When client is nil, it is built from cfg+env.
// When factory is nil, lsp.NewServer is used.
func RunWithFactory(logPath string, stdin io.Reader, stdout io.Writer, logger *log.Logger, cfg appconfig.App, client llm.Client, factory ServerFactory) error {
	// Normalize and apply logging config
	cfg.ContextMode = strings.ToLower(strings.TrimSpace(cfg.ContextMode))
	if cfg.LogPreviewLimit >= 0 {
		logging.SetLogPreviewLimit(cfg.LogPreviewLimit)
	}

	// Build LLM client if not provided
	if client == nil {
		llmCfg := llm.Config{
			Provider:       cfg.Provider,
			OpenAIBaseURL:  cfg.OpenAIBaseURL,
			OpenAIModel:    cfg.OpenAIModel,
			OllamaBaseURL:  cfg.OllamaBaseURL,
			OllamaModel:    cfg.OllamaModel,
			CopilotBaseURL: cfg.CopilotBaseURL,
			CopilotModel:   cfg.CopilotModel,
		}
		oaKey := os.Getenv("OPENAI_API_KEY")
		cpKey := os.Getenv("COPILOT_API_KEY")
		if c, err := llm.NewFromConfig(llmCfg, oaKey, cpKey); err != nil {
			logging.Logf("lsp ", "llm disabled: %v", err)
		} else {
			client = c
			logging.Logf("lsp ", "llm enabled provider=%s model=%s", c.Name(), c.DefaultModel())
		}
	}

	if factory == nil {
		factory = func(r io.Reader, w io.Writer, logger *log.Logger, opts lsp.ServerOptions) ServerRunner {
			return lsp.NewServer(r, w, logger, opts)
		}
	}

	server := factory(stdin, stdout, logger, lsp.ServerOptions{
		LogContext:       strings.TrimSpace(logPath) != "",
		MaxTokens:        cfg.MaxTokens,
		ContextMode:      cfg.ContextMode,
		WindowLines:      cfg.ContextWindowLines,
		MaxContextTokens: cfg.MaxContextTokens,

		Client:            client,
		TriggerCharacters: cfg.TriggerCharacters,
	})
	if err := server.Run(); err != nil {
		logger.Fatalf("server error: %v", err)
	}
	return nil
}