package eghttp

import (
	"context"
	"net"
	"net/http"
	"strconv"
	"sync/atomic"
	"time"
)

const (
	DefaultAddr              = ":8080"
	DefaultReadHeaderTimeout = time.Second
)

type Option interface {
	apply(cfg *config)
}

func WithPort(port int) Option {
	return optionFunc(func(cfg *config) {
		cfg.server.Addr = net.JoinHostPort("", strconv.Itoa(port))
	})
}

func WithHandler(handler http.Handler) Option {
	return optionFunc(func(cfg *config) {
		cfg.server.Handler = handler
	})
}

func WithServer(server *http.Server) Option {
	return optionFunc(func(cfg *config) {
		cfg.server = server
	})
}

func WithStartFn(fn func(server *http.Server) error) Option {
	return optionFunc(func(cfg *config) {
		cfg.startFn = fn
	})
}

// WithServerOption 使用 fn 配置 [http.Server];
func WithServerOption(fn func(server *http.Server)) Option {
	return optionFunc(func(cfg *config) {
		fn(cfg.server)
	})
}

type config struct {
	server  *http.Server
	startFn func(server *http.Server) error
}

func newDefaultConfig() *config {
	return &config{
		server: &http.Server{
			Addr:              DefaultAddr,
			ReadHeaderTimeout: DefaultReadHeaderTimeout,
		},
		startFn: func(server *http.Server) error {
			return server.ListenAndServe()
		},
	}
}

type optionFunc func(cfg *config)

func (fn optionFunc) apply(cfg *config) {
	fn(cfg)
}

// HTTPListenAndServe 创建 [http.Server] 并提供启动和停止函数;
func HTTPListenAndServe(opts ...Option) (func(ctx context.Context) error, func(ctx context.Context)) {
	cfg := newDefaultConfig()
	for _, opt := range opts {
		opt.apply(cfg)
	}
	inShutdown := &atomic.Bool{}
	c := make(chan error, 1)
	goFunc := func(_ context.Context) error {
		err := cfg.startFn(cfg.server)
		if inShutdown.Load() {
			err = <-c
		}
		return err
	}
	stopFunc := func(ctx context.Context) {
		inShutdown.Store(true)
		c <- cfg.server.Shutdown(ctx)
	}
	return goFunc, stopFunc
}