package backup

import (
	"fmt"
	"os"
	"os/exec"
	"strings"

	"gopkg.in/yaml.v3"
)

// StackDataProvider provides stack data to the backup package without circular imports.
type StackDataProvider interface {
	GetStackComposePath(name string) (composePath string, ok bool)
	ListDeployedStacks() []StackSummary
	GetStackHDDMounts(name string) []string
}

// StackSummary holds minimal stack info needed for app data discovery.
type StackSummary struct {
	Name        string
	DisplayName string
	ComposePath string
	NeedsHDD    bool
}

// AppBackupInfo holds backup-relevant data paths for a deployed app.
type AppBackupInfo struct {
	StackName     string
	DisplayName   string
	NeedsHDD      bool
	HDDPaths      []AppDataPath
	HDDTotalSize  int64
	HDDSizeHuman  string
	DockerVolumes []AppDockerVolume
	BackupEnabled bool
	HasHDDData    bool
	HasDBDump     bool
}

// AppDataPath represents a single HDD bind mount path.
type AppDataPath struct {
	HostPath  string
	Exists    bool
	SizeHuman string
	SizeBytes int64
}

// AppDockerVolume represents a named Docker volume.
type AppDockerVolume struct {
	Name     string
	Contains string
}

// DiscoverAppData discovers backup-relevant data for all deployed apps.
func DiscoverAppData(provider StackDataProvider, hddPath string, backupPrefs map[string]bool, discoveredDBs []DiscoveredDB) []AppBackupInfo {
	if provider == nil {
		return nil
	}

	var result []AppBackupInfo

	for _, stack := range provider.ListDeployedStacks() {
		info := AppBackupInfo{
			StackName:   stack.Name,
			DisplayName: stack.DisplayName,
			NeedsHDD:    stack.NeedsHDD,
		}

		// Discover HDD bind mounts via adapter
		hddMounts := provider.GetStackHDDMounts(stack.Name)
		for _, mount := range hddMounts {
			path := AppDataPath{HostPath: mount}
			if fi, err := os.Stat(mount); err == nil && fi.IsDir() {
				path.Exists = true
				path.SizeBytes = appDirSizeBytes(mount)
				path.SizeHuman = appDirSizeHuman(mount)
			}
			info.HDDPaths = append(info.HDDPaths, path)
			info.HDDTotalSize += path.SizeBytes
		}
		info.HDDSizeHuman = humanizeBytes(info.HDDTotalSize)
		info.HasHDDData = len(info.HDDPaths) > 0

		// Discover Docker named volumes from compose
		info.DockerVolumes = parseComposeNamedVolumes(stack.ComposePath)

		// Check if app has a DB container (already backed up via DB dump)
		for _, db := range discoveredDBs {
			if db.StackName == stack.Name {
				info.HasDBDump = true
				break
			}
		}

		info.BackupEnabled = backupPrefs[stack.Name]

		// Only include apps that have some data to show
		if info.HasHDDData || len(info.DockerVolumes) > 0 {
			result = append(result, info)
		}
	}

	return result
}

// parseComposeNamedVolumes extracts named Docker volumes from a docker-compose.yml.
func parseComposeNamedVolumes(composePath string) []AppDockerVolume {
	data, err := os.ReadFile(composePath)
	if err != nil {
		return nil
	}

	var compose struct {
		Volumes map[string]interface{} `yaml:"volumes"`
	}
	if err := yaml.Unmarshal(data, &compose); err != nil {
		return nil
	}

	var volumes []AppDockerVolume
	for name, cfg := range compose.Volumes {
		// Skip external volumes
		if cfgMap, ok := cfg.(map[string]interface{}); ok {
			if ext, ok := cfgMap["external"]; ok && ext == true {
				continue
			}
		}
		volumes = append(volumes, AppDockerVolume{Name: name})
	}
	return volumes
}

// appDirSizeHuman returns a human-readable size string for a directory using du.
func appDirSizeHuman(path string) string {
	cmd := exec.Command("du", "-sh", path)
	output, err := cmd.Output()
	if err != nil {
		return "?"
	}
	fields := strings.Fields(string(output))
	if len(fields) > 0 {
		return fields[0]
	}
	return "?"
}

// appDirSizeBytes returns the total size in bytes for a directory.
func appDirSizeBytes(path string) int64 {
	cmd := exec.Command("du", "-sb", path)
	output, err := cmd.Output()
	if err != nil {
		return 0
	}
	fields := strings.Fields(string(output))
	if len(fields) > 0 {
		var size int64
		fmt.Sscanf(fields[0], "%d", &size)
		return size
	}
	return 0
}

// humanizeBytes converts bytes to a human-readable string.
func humanizeBytes(b int64) string {
	const (
		KB = 1024
		MB = KB * 1024
		GB = MB * 1024
	)
	switch {
	case b >= GB:
		return fmt.Sprintf("%.1f GB", float64(b)/float64(GB))
	case b >= MB:
		return fmt.Sprintf("%.1f MB", float64(b)/float64(MB))
	case b >= KB:
		return fmt.Sprintf("%.1f KB", float64(b)/float64(KB))
	default:
		return fmt.Sprintf("%d B", b)
	}
}