package config

import (
	"log"
	"time"
)

// HTTPConfig controls built-in HTTP servers. Positive values override the
// selected transport's defaults; zero keeps its existing behavior. Timeouts
// follow that transport's semantics, not a handler execution deadline.
type HTTPConfig struct {
	ReadHeaderTimeout time.Duration `json:"readHeaderTimeout"`
	ReadTimeout       time.Duration `json:"readTimeout"`
	WriteTimeout      time.Duration `json:"writeTimeout"`
	IdleTimeout       time.Duration `json:"idleTimeout"`
	MaxHeaderBytes    int           `json:"maxHeaderBytes"`
	// ErrorLog is a Go-only hook for the nethttp server's internal diagnostics.
	ErrorLog *log.Logger `json:"-"`
}

func (c HTTPConfig) Validate() error {
	for _, field := range []struct {
		name  string
		value time.Duration
	}{
		{"readHeaderTimeout", c.ReadHeaderTimeout},
		{"readTimeout", c.ReadTimeout},
		{"writeTimeout", c.WriteTimeout},
		{"idleTimeout", c.IdleTimeout},
	} {
		if field.value < 0 {
			return &ConfigError{Field: "http." + field.name, Message: "must be nonnegative"}
		}
	}
	if c.MaxHeaderBytes < 0 {
		return &ConfigError{Field: "http.maxHeaderBytes", Message: "must be nonnegative"}
	}
	return nil
}

// WithHTTPConfig sets the built-in server's HTTP options. RunWith uses a
// caller-owned Runner and does not apply these options to that runner.
func WithHTTPConfig(settings HTTPConfig) Option {
	return func(cfg *Config) { cfg.HTTP = settings }
}