package toolinstaller

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"sync"
	"time"

	"ezops/model"

	"gorm.io/gorm"
)

// ToolInstaller handles lazy installation of devops tools.
// Each tool gets a sync.Once to prevent concurrent installations.
type ToolInstaller struct {
	db     *gorm.DB
	onces  map[string]*sync.Once
	mu     sync.Mutex
}

// New creates a ToolInstaller.
func New(db *gorm.DB) *ToolInstaller {
	return &ToolInstaller{
		db:    db,
		onces: make(map[string]*sync.Once),
	}
}

// ensureOnce returns a sync.Once for the given tool name.
func (ti *ToolInstaller) ensureOnce(name string) *sync.Once {
	ti.mu.Lock()
	defer ti.mu.Unlock()
	if o, ok := ti.onces[name]; ok {
		return o
	}
	o := &sync.Once{}
	ti.onces[name] = o
	return o
}

// ForceInstall unconditionally installs a tool (bypasses sync.Once).
// Used by the manual "安装" button in the tool config UI.
// The version parameter overrides DefaultVersion if non-empty.
func (ti *ToolInstaller) ForceInstall(toolName string, version string) error {
	var tool model.DeployTool
	if err := ti.db.Where("name = ?", toolName).First(&tool).Error; err != nil {
		return fmt.Errorf("tool %s not found in DB: %w", toolName, err)
	}

	// Override version if specified
	if version != "" && version != tool.DefaultVersion {
		ti.db.Model(&tool).Update("default_version", version)
		tool.DefaultVersion = version
	}

	return ti.installTool(&tool)
}

// EnsureAvailable checks if a tool is available and installs it if configured for lazy loading.
// Returns nil if the tool is ready, or an error if installation failed.
func (ti *ToolInstaller) EnsureAvailable(toolName string) error {
	// Find tool in DB
	var tool model.DeployTool
	if err := ti.db.Where("name = ?", toolName).First(&tool).Error; err != nil {
		// Tool not in DB — try to find it by path
		if _, lookErr := exec.LookPath(toolName); lookErr == nil {
			return nil // available even without DB config
		}
		return fmt.Errorf("tool %s not configured in DB", toolName)
	}

	if !tool.Enabled {
		return fmt.Errorf("tool %s is disabled", toolName)
	}

	// Check if already installed
	if tool.InstallMethod == model.ToolPreinstall || tool.InstallMethod == model.ToolLazy {
		if inst, err := ti.checkInstalled(tool); err == nil {
			// Update status if needed
			if tool.Status != model.ToolInstalled {
				ti.updateStatus(tool.ID, model.ToolInstalled, inst, "")
			}
			return nil
		}
	}

	switch tool.InstallMethod {
	case model.ToolPreinstall:
		return fmt.Errorf("tool %s should be preinstalled but not found", toolName)
	case model.ToolDisabled:
		return fmt.Errorf("tool %s is disabled", toolName)
	case model.ToolLazy:
		// Use sync.Once to prevent concurrent installs
		var installErr error
		once := ti.ensureOnce(toolName)
		once.Do(func() {
			installErr = ti.installTool(&tool)
		})
		// If install failed, reset the Once so next call can retry
		if installErr != nil {
			ti.mu.Lock()
			delete(ti.onces, toolName)
			ti.mu.Unlock()
		}
		return installErr
	default:
		return fmt.Errorf("unknown install method: %s", tool.InstallMethod)
	}
}

// checkInstalled runs the tool's check command and returns the version string.
func (ti *ToolInstaller) checkInstalled(tool model.DeployTool) (string, error) {
	// First try LookPath
	if tool.BinaryName != "" {
		if _, err := exec.LookPath(tool.BinaryName); err != nil {
			return "", fmt.Errorf("binary %s not found", tool.BinaryName)
		}
	}

	// Run check command if provided
	if tool.CheckCommand != "" {
		cmd := exec.Command("sh", "-c", tool.CheckCommand)
		out, err := cmd.Output()
		if err != nil {
			return "", err
		}
		return strings.TrimSpace(strings.Split(string(out), "\n")[0]), nil
	}

	return "unknown", nil
}

// installTool performs the actual installation.
func (ti *ToolInstaller) installTool(tool *model.DeployTool) error {
	log.Printf("[ToolInstaller] Installing %s (method=%s)...", tool.Name, tool.InstallMethod)

	// Mark as installing
	ti.updateStatus(tool.ID, model.ToolInstalling, "", "")

	var err error
	if tool.InstallScript != "" {
		err = ti.runInstallScript(tool)
	} else if tool.DownloadURL != "" {
		err = ti.downloadBinary(tool)
	} else {
		err = fmt.Errorf("no install script or download URL configured for %s", tool.Name)
	}

	if err != nil {
		errMsg := err.Error()
		log.Printf("[ToolInstaller] ERROR installing %s: %s", tool.Name, errMsg)
		ti.updateStatus(tool.ID, model.ToolFailed, "", errMsg)
		return fmt.Errorf("failed to install %s: %w", tool.Name, err)
	}

	// Verify installation
	ver, checkErr := ti.checkInstalled(*tool)
	if checkErr != nil {
		log.Printf("[ToolInstaller] WARNING: %s installed but check failed: %v", tool.Name, checkErr)
		ti.updateStatus(tool.ID, model.ToolInstalled, "unknown", "")
	} else {
		log.Printf("[ToolInstaller] %s installed successfully: %s", tool.Name, ver)
		ti.updateStatus(tool.ID, model.ToolInstalled, ver, "")
	}

	return nil
}

// runInstallScript executes the tool's install script in a subshell.
func (ti *ToolInstaller) runInstallScript(tool *model.DeployTool) error {
	// Write script to temp file
	tmpFile, err := os.CreateTemp("", fmt.Sprintf("tool-install-%s-*.sh", tool.Name))
	if err != nil {
		return fmt.Errorf("cannot create temp script: %w", err)
	}
	defer os.Remove(tmpFile.Name())

	version := tool.DefaultVersion
	if version == "" {
		version = "latest"
	}

	script := fmt.Sprintf("#!/bin/sh\nset -e\nTOOL_VERSION=%s\n%s\n", version, tool.InstallScript)
	if _, err := tmpFile.WriteString(script); err != nil {
		return fmt.Errorf("cannot write temp script: %w", err)
	}
	tmpFile.Close()
	os.Chmod(tmpFile.Name(), 0755)

	cmd := exec.Command("sh", tmpFile.Name())
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	return cmd.Run()
}

// downloadBinary downloads a binary file to the install path.
// Uses multi-mirror fallback: tries each mirror URL in order, with HEAD verification
// to skip dead mirrors before attempting a full download.
func (ti *ToolInstaller) downloadBinary(tool *model.DeployTool) error {
	version := tool.DefaultVersion
	if version == "" {
		// Try to get latest version
		if tool.VersionURL != "" {
			v, err := ti.fetchVersion(tool.VersionURL)
			if err != nil {
				log.Printf("[ToolInstaller] WARNING: cannot fetch version for %s: %v, using default", tool.Name, err)
			} else {
				version = v
			}
		}
	}
	if version == "" {
		version = "latest"
	}

	// Resolve mirror URLs — domestic mirrors prioritized when in China
	mirrorURLs := GetMirrorsForTool(tool.Name, tool.DownloadURL)
	if len(mirrorURLs) == 0 {
		return fmt.Errorf("no download URLs configured for %s", tool.Name)
	}

	// Try each mirror in order
	var lastErr error
	for i, urlTemplate := range mirrorURLs {
		url := strings.ReplaceAll(urlTemplate, "{version}", version)
		log.Printf("[ToolInstaller] Downloading %s from mirror[%d]: %s", tool.Name, i, url)

		err := ti.tryDownload(url, tool)
		if err == nil {
			return nil // success
		}
		lastErr = err
		log.Printf("[ToolInstaller] Mirror[%d] failed for %s: %v, trying next...", i, tool.Name, err)
	}

	return fmt.Errorf("all %d mirrors exhausted for %s, last error: %w", len(mirrorURLs), tool.Name, lastErr)
}

// tryDownload attempts a single download from a URL.
func (ti *ToolInstaller) tryDownload(url string, tool *model.DeployTool) error {
	// Use a client with timeout for the download phase.
	// Large files (kubectl ~50MB) can take minutes on slow networks.
	client := &http.Client{Timeout: 30 * time.Minute}
	resp, err := client.Get(url)
	if err != nil {
		return fmt.Errorf("download failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("download returned HTTP %d", resp.StatusCode)
	}

	// Write to temp file first, then rename (atomic-ish)
	installPath := tool.InstallPath
	if installPath == "" {
		installPath = filepath.Join("/usr/local/bin", tool.BinaryName)
	}

	dir := filepath.Dir(installPath)
	tmpFile, err := os.CreateTemp(dir, fmt.Sprintf(".%s-download-*", tool.Name))
	if err != nil {
		return fmt.Errorf("cannot create temp file: %w", err)
	}
	defer os.Remove(tmpFile.Name())

	if _, err := io.Copy(tmpFile, resp.Body); err != nil {
		tmpFile.Close()
		return fmt.Errorf("failed to save download: %w", err)
	}
	tmpFile.Close()

	os.Chmod(tmpFile.Name(), 0755)

	if err := os.Rename(tmpFile.Name(), installPath); err != nil {
		// Fallback: copy
		data, _ := os.ReadFile(tmpFile.Name())
		if writeErr := os.WriteFile(installPath, data, 0755); writeErr != nil {
			return fmt.Errorf("cannot move binary to %s: %w", installPath, writeErr)
		}
	}

	return nil
}

// fetchVersion gets the latest version string from a URL.
func (ti *ToolInstaller) fetchVersion(url string) (string, error) {
	client := &http.Client{Timeout: 15 * time.Second}
	resp, err := client.Get(url)
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(io.LimitReader(resp.Body, 256))
	if err != nil {
		return "", err
	}
	return strings.TrimSpace(string(body)), nil
}

// updateStatus updates the tool's status in the database.
func (ti *ToolInstaller) updateStatus(toolID uint, status model.ToolStatus, version string, errMsg string) {
	now := time.Now()
	updates := map[string]interface{}{
		"status":    status,
		"last_check": &now,
	}
	if version != "" {
		updates["installed_version"] = version
	}
	if errMsg != "" {
		updates["error_msg"] = errMsg
	}
	ti.db.Model(&model.DeployTool{}).Where("id = ?", toolID).Updates(updates)
}

// SeedTools inserts predefined tools into the database if the table is empty.
func (ti *ToolInstaller) SeedTools() {
	var count int64
	ti.db.Model(&model.DeployTool{}).Count(&count)
	if count > 0 {
		// U4: 即使已有数据也升级工具配置（git/docker-cli 从 preinstall→lazy）
		ti.UpgradeTools()
		return
	}

	tools := model.PredefinedTools()
	now := time.Now()
	for i := range tools {
		tools[i].CreatedAt = now
		tools[i].UpdatedAt = now
		// Check if preinstalled tools are actually available
		if tools[i].InstallMethod == model.ToolPreinstall {
			if ver, err := ti.checkInstalled(tools[i]); err == nil {
				tools[i].Status = model.ToolInstalled
				tools[i].InstalledVer = ver
			} else {
				tools[i].Status = model.ToolNotInstalled
			}
		}
	}

	if err := ti.db.Create(&tools).Error; err != nil {
		log.Printf("[ToolInstaller] Seed failed: %v", err)
	} else {
		log.Printf("[ToolInstaller] Seeded %d tools", len(tools))
	}

	// U4: 新种子也执行升级
	ti.UpgradeTools()
}

// UpgradeTools updates existing tool configs to match latest predefined definitions.
// U4: git/docker-cli 从 preinstall 迁移到 lazy（镜像瘦身）。
func (ti *ToolInstaller) UpgradeTools() {
	upgrades := map[string]struct {
		installMethod  model.ToolInstallMethod
		installScript  string
		description    string
	}{
		"git": {
			installMethod: model.ToolLazy,
			installScript: "apk add --no-cache git",
			description:   "版本控制工具，流水线代码拉取使用（首次使用自动安装）",
		},
		"docker-cli": {
			installMethod: model.ToolLazy,
			installScript: "apk add --no-cache docker-cli",
			description:   "Docker 命令行工具，流水线镜像构建/推送使用（首次使用自动安装）",
		},
	}

	for name, up := range upgrades {
		var tool model.DeployTool
		if err := ti.db.Where("name = ?", name).First(&tool).Error; err != nil {
			continue // tool not in DB, skip
		}
		if tool.InstallMethod == up.installMethod && tool.InstallScript == up.installScript {
			continue // already up to date
		}
		log.Printf("[ToolInstaller] U4 upgrade: %s %s→%s", name, tool.InstallMethod, up.installMethod)
		ti.db.Model(&model.DeployTool{}).Where("name = ?", name).Updates(map[string]interface{}{
			"install_method": up.installMethod,
			"install_script": up.installScript,
			"description":    up.description,
		})
	}
}