package config

import (
	"log"
	"time"

	"git.yuntuo.hk/k2safe/go-omni/internal/httplimits"
)

// HTTPConfig controls HTTP serving. Network timeouts follow the selected
// transport's semantics, not a handler execution deadline. Body limits and
// shutdown cancellation grace also apply to App used with an external server.
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"`
	// DefaultMaxBodyBytes applies to App routes without an explicit limit.
	// Zero uses 8 MiB, or the hard limit if smaller. Route limits may override it.
	DefaultMaxBodyBytes int64 `json:"defaultMaxBodyBytes"`
	// MaxBodyBytes is an optional service hard limit. Zero adds no hard limit
	// below the framework's supported maximum of 1 TiB.
	MaxBodyBytes int64 `json:"maxBodyBytes"`
	// ShutdownCancelTimeout bounds the wait for handlers after cancellation.
	// Zero uses 5s. Resources are retained if handlers have not returned.
	ShutdownCancelTimeout time.Duration `json:"shutdownCancelTimeout"`
	// 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},
		{"shutdownCancelTimeout", c.ShutdownCancelTimeout},
	} {
		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"}
	}
	for _, field := range []struct {
		name  string
		value int64
	}{{"defaultMaxBodyBytes", c.DefaultMaxBodyBytes}, {"maxBodyBytes", c.MaxBodyBytes}} {
		if field.value < 0 || field.value > httplimits.MaxBodyBytes {
			return &ConfigError{Field: "http." + field.name, Message: "must be 0..1 TiB (bytes)"}
		}
	}
	if c.MaxBodyBytes > 0 && c.DefaultMaxBodyBytes > c.MaxBodyBytes {
		return &ConfigError{Field: "http.defaultMaxBodyBytes", Message: "must not exceed http.maxBodyBytes"}
	}
	return nil
}

// WithHTTPConfig sets HTTP options. RunWith leaves network configuration to the
// caller-owned Runner, but App body limits and cancellation grace still apply.
func WithHTTPConfig(settings HTTPConfig) Option {
	return func(cfg *Config) { cfg.HTTP = settings }
}