package aitools

import (
	"encoding/json"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strings"
	"time"
)

const npmPackageName = "@rlwj-lab/opsxdb-mcp"

// MCPInstallInfo 设置 → MCP 页的安装/环境检测结果。
type MCPInstallInfo struct {
	Status              string `json:"status"` // ready | not_installed | partial
	Installed           bool   `json:"installed"`
	CurrentVersion      string `json:"currentVersion,omitempty"`
	LatestVersion       string `json:"latestVersion,omitempty"`
	NodeVersion         string `json:"nodeVersion,omitempty"`
	NpmAvailable        bool   `json:"npmAvailable"`
	NpmVersion          string `json:"npmVersion,omitempty"`
	NpmPackageInstalled bool   `json:"npmPackageInstalled"`
	NpmPackageVersion   string `json:"npmPackageVersion,omitempty"`
	GoBinaryFound       bool   `json:"goBinaryFound"`
	GoBinaryPath        string `json:"goBinaryPath,omitempty"`
	InstallCommand      string `json:"installCommand"`
	NpxCommand          string `json:"npxCommand"`
	PolicyPath          string `json:"policyPath,omitempty"`
	Hint                string `json:"hint,omitempty"`
}

// ProbeMCPInstall 检测 Node/npm、全局 npm 包、Go 二进制与 registry 最新版。
func ProbeMCPInstall() MCPInstallInfo {
	info := MCPInstallInfo{
		Status:         "not_installed",
		InstallCommand: "npm install -g " + npmPackageName + "@latest",
		NpxCommand:     "npx -y " + npmPackageName,
	}
	if p, err := PolicyPath(); err == nil {
		info.PolicyPath = p
	}

	node, nodeVer := findToolVersion("node", "--version")
	npm, npmVer := findToolVersion("npm", "--version")
	info.NodeVersion = strings.TrimPrefix(strings.TrimSpace(nodeVer), "v")
	if node != "" && info.NodeVersion != "" {
		info.NodeVersion = "v" + strings.TrimPrefix(info.NodeVersion, "v")
	}
	info.NpmAvailable = npm != ""
	info.NpmVersion = strings.TrimSpace(npmVer)

	if bin := resolveGoMCPBinary(); bin != "" {
		info.GoBinaryFound = true
		info.GoBinaryPath = bin
	}

	if npm != "" {
		ver := npmGlobalPackageVersion(npm, npmPackageName)
		if ver != "" {
			info.NpmPackageInstalled = true
			info.NpmPackageVersion = ver
			info.CurrentVersion = ver
		}
	}
	if info.CurrentVersion == "" && info.GoBinaryFound {
		info.CurrentVersion = "native"
	}

	info.LatestVersion = fetchLatestNpmVersion(npmPackageName)

	switch {
	case info.GoBinaryFound && (info.NpmPackageInstalled || info.NpmAvailable):
		info.Status = "ready"
		info.Installed = true
		if !info.NpmPackageInstalled {
			info.Hint = "已找到 Go 二进制；建议再 npm i -g，或用 npx + OPSXDB_MCP_BIN。"
		}
	case info.GoBinaryFound:
		info.Status = "partial"
		info.Installed = true
		info.Hint = "已找到 Go 二进制，但未检测到 Node/npm。客户端可用绝对路径启动二进制。"
	case info.NpmPackageInstalled:
		info.Status = "partial"
		info.Installed = false
		info.Hint = "npm 包已装，但未找到 Go 二进制。请 go build 后设置 OPSXDB_MCP_BIN。"
	case info.NpmAvailable:
		info.Status = "not_installed"
		info.Hint = "检测到 Node/npm，尚未安装 MCP 包或 Go 二进制。"
	default:
		info.Status = "not_installed"
		info.Hint = "未检测到 Node.js。请安装 Node 18+，或直接用 Go 二进制绝对路径配置客户端。"
	}
	return info
}

func findToolVersion(name string, versionArg string) (bin, version string) {
	bin = lookPathAugmented(name)
	if bin == "" {
		return "", ""
	}
	out, err := exec.Command(bin, versionArg).CombinedOutput()
	if err != nil {
		return bin, ""
	}
	return bin, strings.TrimSpace(string(out))
}

func lookPathAugmented(name string) string {
	if p, err := exec.LookPath(name); err == nil {
		return p
	}
	home, _ := os.UserHomeDir()
	var extras []string
	if home != "" {
		nvm := filepath.Join(home, ".nvm", "versions", "node")
		if ents, err := os.ReadDir(nvm); err == nil {
			for _, e := range ents {
				if e.IsDir() {
					extras = append(extras, filepath.Join(nvm, e.Name(), "bin"))
				}
			}
		}
		extras = append(extras,
			filepath.Join(home, ".local", "bin"),
			filepath.Join(home, "bin"),
			"/opt/homebrew/bin",
			"/usr/local/bin",
		)
	}
	pathEnv := os.Getenv("PATH")
	aug := strings.Join(extras, string(os.PathListSeparator))
	if pathEnv != "" {
		aug = aug + string(os.PathListSeparator) + pathEnv
	}
	cmd := exec.Command(name, "--version")
	cmd.Env = append(os.Environ(), "PATH="+aug)
	// Prefer LookPath with augmented PATH
	for _, dir := range extras {
		cand := filepath.Join(dir, name)
		if runtime.GOOS == "windows" {
			cand += ".exe"
		}
		if st, err := os.Stat(cand); err == nil && !st.IsDir() {
			return cand
		}
	}
	if p, err := exec.LookPath(name); err == nil {
		return p
	}
	_ = cmd
	return ""
}

func npmGlobalPackageVersion(npmBin, pkg string) string {
	out, err := exec.Command(npmBin, "list", "-g", pkg, "--depth=0", "--json").CombinedOutput()
	if err != nil && len(out) == 0 {
		return ""
	}
	var raw struct {
		Dependencies map[string]struct {
			Version string `json:"version"`
		} `json:"dependencies"`
	}
	if json.Unmarshal(out, &raw) != nil {
		return ""
	}
	if d, ok := raw.Dependencies[pkg]; ok {
		return d.Version
	}
	return ""
}

func fetchLatestNpmVersion(pkg string) string {
	client := &http.Client{Timeout: 4 * time.Second}
	url := "https://registry.npmjs.org/" + pkg + "/latest"
	req, err := http.NewRequest(http.MethodGet, url, nil)
	if err != nil {
		return ""
	}
	req.Header.Set("Accept", "application/json")
	res, err := client.Do(req)
	if err != nil {
		return ""
	}
	defer res.Body.Close()
	if res.StatusCode != 200 {
		return ""
	}
	var raw struct {
		Version string `json:"version"`
	}
	if json.NewDecoder(res.Body).Decode(&raw) != nil {
		return ""
	}
	return raw.Version
}

func resolveGoMCPBinary() string {
	if env := strings.TrimSpace(os.Getenv("OPSXDB_MCP_BIN")); env != "" {
		if isLikelyNativeBinary(env) {
			return env
		}
	}
	if p, err := exec.LookPath("opsxdb-mcp"); err == nil && isLikelyNativeBinary(p) {
		return p
	}
	home, _ := os.UserHomeDir()
	cands := []string{}
	if home != "" {
		cands = append(cands,
			filepath.Join(home, "devops", "opsxdb", "bin", "opsxdb-mcp"),
			filepath.Join(home, ".opsxdb", "bin", "opsxdb-mcp"),
			filepath.Join(home, ".local", "bin", "opsxdb-mcp"),
		)
	}
	// Relative to running server binary (src-tauri/binaries or server/)
	if exe, err := os.Executable(); err == nil {
		dir := filepath.Dir(exe)
		cands = append(cands,
			filepath.Join(dir, "opsxdb-mcp"),
			filepath.Join(dir, "..", "opsxdb-mcp"),
			filepath.Join(dir, "..", "..", "bin", "opsxdb-mcp"),
			filepath.Join(dir, "..", "..", "..", "bin", "opsxdb-mcp"),
		)
	}
	cands = append(cands, "/usr/local/bin/opsxdb-mcp", "/opt/homebrew/bin/opsxdb-mcp")
	for _, c := range cands {
		if isLikelyNativeBinary(c) {
			return c
		}
	}
	return ""
}

func isLikelyNativeBinary(path string) bool {
	st, err := os.Stat(path)
	if err != nil || st.IsDir() {
		return false
	}
	f, err := os.Open(path)
	if err != nil {
		return false
	}
	defer f.Close()
	buf := make([]byte, 8)
	n, _ := f.Read(buf)
	if n < 2 {
		return false
	}
	// shebang → script
	if buf[0] == '#' && buf[1] == '!' {
		return false
	}
	if n >= 4 && buf[0] == 0x7f && buf[1] == 'E' && buf[2] == 'L' && buf[3] == 'F' {
		return true
	}
	if buf[0] == 'M' && buf[1] == 'Z' {
		return true
	}
	if n >= 4 {
		be := uint32(buf[0])<<24 | uint32(buf[1])<<16 | uint32(buf[2])<<8 | uint32(buf[3])
		le := uint32(buf[3])<<24 | uint32(buf[2])<<16 | uint32(buf[1])<<8 | uint32(buf[0])
		macho := map[uint32]bool{
			0xfeedfacf: true, 0xcffaedfe: true, 0xfeedface: true, 0xcefaedfe: true,
			0xcafebabe: true, 0xbebafeca: true, 0xcafebabf: true, 0xbfbafeca: true,
		}
		if macho[be] || macho[le] {
			return true
		}
	}
	return false
}