package cli

import (
	"context"
	"flag"
	"fmt"
	"log/slog"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/Atte149/ollama-proxy/internal/config"
	"github.com/Atte149/ollama-proxy/internal/log"
	"github.com/Atte149/ollama-proxy/internal/proxy"
)

// RunServe starts the proxy HTTP server.
func RunServe(args []string) int {
	fs := flag.NewFlagSet("serve", flag.ContinueOnError)
	addr := fs.String("addr", "", "listen address (default 127.0.0.1:11435)")
	baseURL := fs.String("base-url", "", "upstream root (default https://ollama.com)")
	cooldown := fs.Duration("cooldown", 0, "per-account 429 cooldown window")
	retries := fs.Int("retries", 0, "max failover attempts")
	logLevel := fs.String("log-level", "", "debug|info|warn|error")
	if err := fs.Parse(args); err != nil {
		fmt.Fprintln(os.Stderr, err)
		return 2
	}

	cfg := config.DefaultServerConfig()
	if *addr != "" {
		cfg.Addr = *addr
	}
	if *baseURL != "" {
		cfg.BaseURL = *baseURL
	}
	if *cooldown > 0 {
		cfg.Cooldown = *cooldown
	}
	if *retries > 0 {
		cfg.Retries = *retries
	}
	if *logLevel != "" {
		cfg.LogLevel = *logLevel
	}
	cfg.ApplyEnv()
	if err := cfg.Validate(); err != nil {
		fmt.Fprintln(os.Stderr, "config error:", err)
		return 2
	}

	logger := log.New(cfg.LogLevel)

	af, err := config.LoadAccounts()
	if err != nil {
		logger.Error("load accounts failed", "err", err)
		return 1
	}
	if len(af.Accounts) == 0 {
		logger.Error("no accounts configured; run `ollama-proxy accounts add` first")
		return 1
	}
	// Per-file BaseURL override wins over flag/env when set.
	if af.BaseURL != "" {
		cfg.BaseURL = af.BaseURL
	}

	balancer := proxy.NewBalancer(af.Accounts, cfg.Cooldown)
	handler := proxy.NewHandler(balancer, cfg.BaseURL, cfg.Retries, logger)

	srv := &http.Server{
		Addr:    cfg.Addr,
		Handler: handler,
		// No ReadTimeout/WriteTimeout: streaming chat may be idle for long
		// periods between tokens. The http.Server's default idle timeout (60s)
		// applies between reads; if that becomes a problem we'll add a per-read
		// deadline via a wrapped Transport, not a global timeout.
	}

	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()

	go func() {
		logger.Info("ollama-proxy starting",
			"addr", cfg.Addr, "upstream", cfg.BaseURL,
			"accounts", balancer.Len(), "cooldown", cfg.Cooldown.String(),
			"retries", cfg.Retries, "log_level", cfg.LogLevel)
		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			logger.Error("server error", "err", err)
			stop()
		}
	}()

	<-ctx.Done()
	logger.Info("shutdown signal received, draining…")
	shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	if err := srv.Shutdown(shutdownCtx); err != nil {
		logger.Error("graceful shutdown failed", "err", err)
		return 1
	}
	logger.Info("stopped")
	return 0
}

// keep slog referenced even if logger.go ever drops it
var _ = slog.LevelInfo