package cloud

import (
	"crypto/hmac"
	"crypto/sha1"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"math/rand"
	"net/http"
	"net/url"
	"sort"
	"strings"
	"time"
)

// AliyunProvider 阿里云 ECS Provider
type AliyunProvider struct {
	accessKey string
	secretKey string
	version   string // API 版本
}

func NewAliyunProvider(accessKey, secretKey string) *AliyunProvider {
	return &AliyunProvider{
		accessKey: accessKey,
		secretKey: secretKey,
		version:   "2014-05-26",
	}
}

func (a *AliyunProvider) Name() string { return "aliyun" }

// percentEncode 阿里云 RPC 签名专用 URL 编码
func percentEncode(s string) string {
	s = url.QueryEscape(s)
	s = strings.ReplaceAll(s, "+", "%20")
	s = strings.ReplaceAll(s, "*", "%2A")
	s = strings.ReplaceAll(s, "%7E", "~")
	return s
}

// sign 计算阿里云 RPC v1 HMAC-SHA1 签名
func (a *AliyunProvider) sign(params map[string]string) string {
	// 1. 排序参数 key
	keys := make([]string, 0, len(params))
	for k := range params {
		keys = append(keys, k)
	}
	sort.Strings(keys)

	// 2. 拼接规范化查询字符串
	var pairs []string
	for _, k := range keys {
		pairs = append(pairs, percentEncode(k)+"="+percentEncode(params[k]))
	}
	canonicalized := strings.Join(pairs, "&")

	// 3. 构造待签名字符串
	stringToSign := "GET&" + percentEncode("/") + "&" + percentEncode(canonicalized)

	// 4. HMAC-SHA1
	mac := hmac.New(sha1.New, []byte(a.secretKey+"&"))
	mac.Write([]byte(stringToSign))
	return base64.StdEncoding.EncodeToString(mac.Sum(nil))
}

// call 调用阿里云 RPC API
func (a *AliyunProvider) call(action string, extra map[string]string, endpoint string) ([]byte, error) {
	if endpoint == "" {
		endpoint = "https://ecs.aliyuncs.com/"
	}

	params := map[string]string{
		"Format":           "JSON",
		"Version":          a.version,
		"AccessKeyId":      a.accessKey,
		"SignatureMethod":  "HMAC-SHA1",
		"Timestamp":        time.Now().UTC().Format("2006-01-02T15:04:05Z"),
		"SignatureVersion": "1.0",
		"SignatureNonce":   fmt.Sprintf("%d", rand.Int63()),
		"Action":           action,
	}
	for k, v := range extra {
		params[k] = v
	}
	params["Signature"] = a.sign(params)

	// 构造 GET URL
	var pairs []string
	for k, v := range params {
		pairs = append(pairs, url.QueryEscape(k)+"="+url.QueryEscape(v))
	}
	reqURL := endpoint + "?" + strings.Join(pairs, "&")

	resp, err := http.Get(reqURL)
	if err != nil {
		return nil, fmt.Errorf("请求阿里云 API 失败: %w", err)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("读取响应失败: %w", err)
	}

	if resp.StatusCode != 200 {
		return nil, fmt.Errorf("阿里云 API 返回错误 (HTTP %d): %s", resp.StatusCode, string(body))
	}
	return body, nil
}

// aliyunRegionsResponse DescribeRegions 响应
type aliyunRegionsResponse struct {
	Regions struct {
		Region []struct {
			RegionID       string `json:"RegionId"`
			LocalName      string `json:"LocalName"`
			RegionEndpoint string `json:"RegionEndpoint"`
		} `json:"Region"`
	} `json:"Regions"`
}

// ListRegions 获取阿里云所有区域
func (a *AliyunProvider) ListRegions() ([]CloudRegion, error) {
	body, err := a.call("DescribeRegions", nil, "")
	if err != nil {
		return nil, err
	}

	var resp aliyunRegionsResponse
	if err := json.Unmarshal(body, &resp); err != nil {
		return nil, fmt.Errorf("解析区域响应失败: %w", err)
	}

	regions := make([]CloudRegion, 0, len(resp.Regions.Region))
	for _, r := range resp.Regions.Region {
		regions = append(regions, CloudRegion{
			RegionID:  r.RegionID,
			LocalName: r.LocalName,
			Endpoint:  r.RegionEndpoint,
			Status:    "active",
		})
	}
	return regions, nil
}

// aliyunInstancesResponse DescribeInstances 响应
type aliyunInstancesResponse struct {
	TotalCount int `json:"TotalCount"`
	Instances  struct {
		Instance []struct {
			InstanceID   string `json:"InstanceId"`
			InstanceName string `json:"InstanceName"`
			HostName     string `json:"HostName"`
			Status       string `json:"Status"`
			RegionID     string `json:"RegionId"`
			ZoneID       string `json:"ZoneId"`
			InstanceType string `json:"InstanceType"`
			CPU          int    `json:"Cpu"`
			Memory       int    `json:"Memory"`
			OSType       string `json:"OSType"`
			CreationTime string `json:"CreationTime"`

			VPCAttributes struct {
				PrivateIPAddress struct {
					IPAddress []string `json:"IpAddress"`
				} `json:"PrivateIpAddress"`
			} `json:"VpcAttributes"`

			PublicIPAddress struct {
				IPAddress []string `json:"IpAddress"`
			} `json:"PublicIpAddress"`

			InnerIPAddress struct {
				IPAddress []string `json:"IpAddress"`
			} `json:"InnerIpAddress"`
		} `json:"Instance"`
	} `json:"Instances"`
}

// ListInstances 获取指定区域的云主机实例
func (a *AliyunProvider) ListInstances(regionID string) ([]CloudInstance, error) {
	endpoint := fmt.Sprintf("https://ecs.%s.aliyuncs.com/", regionID)

	body, err := a.call("DescribeInstances", map[string]string{
		"RegionId":   regionID,
		"PageSize":   "100",
	}, endpoint)
	if err != nil {
		return nil, err
	}

	var resp aliyunInstancesResponse
	if err := json.Unmarshal(body, &resp); err != nil {
		return nil, fmt.Errorf("解析实例响应失败: %w", err)
	}

	instances := make([]CloudInstance, 0, len(resp.Instances.Instance))
	for _, inst := range resp.Instances.Instance {
		privateIP := ""
		if len(inst.VPCAttributes.PrivateIPAddress.IPAddress) > 0 {
			privateIP = inst.VPCAttributes.PrivateIPAddress.IPAddress[0]
		}
		publicIP := ""
		if len(inst.PublicIPAddress.IPAddress) > 0 {
			publicIP = inst.PublicIPAddress.IPAddress[0]
		}
		osType := inst.OSType
		if osType == "" {
			osType = "linux"
		}

		instances = append(instances, CloudInstance{
			InstanceID:   inst.InstanceID,
			InstanceName: inst.InstanceName,
			Hostname:     inst.HostName,
			OSType:       osType,
			Status:       inst.Status,
			RegionID:     inst.RegionID,
			ZoneID:       inst.ZoneID,
			PrivateIP:    privateIP,
			PublicIP:     publicIP,
			InstanceType: inst.InstanceType,
			CPU:          inst.CPU,
			Memory:       inst.Memory,
			CreationTime: inst.CreationTime,
		})
	}
	return instances, nil
}