package router

import (
	"fmt"
	"reflect"
	"strings"
)

type Header map[string][]string

func (h Header) Parse(data any) {
	if h == nil {
		h = make(Header)
	}
	d := reflect.ValueOf(data)
	if d.Kind() != reflect.Struct {
		panic(fmt.Errorf("expected struct input for data"))
	}
	for i := 0; i < d.NumField(); i++ {
		key, ok := d.Type().Field(i).Tag.Lookup("header")
		if !ok || key == "" {
			continue
		}
		v := make([]string, 0)
		val := d.Field(i)
		if val.Kind() == reflect.Pointer || val.Kind() == reflect.Interface {
			val = val.Elem()
		}
		if val.Kind() == reflect.Slice || val.Kind() == reflect.Array {
			for j := 0; j < val.Len(); j++ {
				item := val.Index(j)
				if item.Kind() == reflect.Pointer || item.Kind() == reflect.Interface {
					item = item.Elem()
				}
				v = append(v, fmt.Sprintf("%s", item.Interface()))
			}
		} else {
			v = append(v, fmt.Sprintf("%s", val.Interface()))
		}
		h[key] = v
	}
}

func (h Header) Get(key string) (value string) {
	v, ok := h[key]
	if !ok {
		return
	}
	return strings.Join(v, ", ")
}

func (h Header) Set(key string, value string) {
	h[key] = []string{value}
}

func (h Header) Add(key string, value string) {
	h[key] = append(h[key], value)
}

func (h Header) Merge(header Header) {
	for key, value := range header {
		if _, exists := h[key]; exists {
			continue
		}
		h[key] = value
	}
}

func (h Header) MergeOverwrite(header Header) {
	for key, value := range header {
		h[key] = value
	}
}