package eghttp

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

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

type Option interface {
	apply(server *http.Server)
}

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

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

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

type optionFunc func(server *http.Server)

func (fn optionFunc) apply(server *http.Server) {
	fn(server)
}

// HTTPListenAndServe 创建 [http.Server] 并提供启动和停止函数;
// opts 按照顺序应用到 [http.Server] 上.
func HTTPListenAndServe(opts ...Option) (func(ctx context.Context) error, func(ctx context.Context)) {
	server := &http.Server{
		Addr:              DefaultAddr,
		ReadHeaderTimeout: DefaultReadHeaderTimeout,
	}
	for _, opt := range opts {
		opt.apply(server)
	}
	return HTTPServer(server)
}

// HTTPServer 提供 [http.Server] 的启动和停止函数;
func HTTPServer(server *http.Server) (func(ctx context.Context) error, func(ctx context.Context)) {
	inShutdown := &atomic.Bool{}
	c := make(chan error, 1)
	goFunc := func(_ context.Context) error {
		err := server.ListenAndServe()
		if inShutdown.Load() {
			err = <-c
		}
		return err
	}
	stopFunc := func(ctx context.Context) {
		inShutdown.Store(true)
		c <- server.Shutdown(ctx)
	}
	return goFunc, stopFunc
}