package cli

import (
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"

	"github.com/spf13/cobra"
	"gopkg.in/yaml.v3"
)

const defaultConfigTemplate = `# vaultik configuration
# Documentation: https://sneak.berlin/go/vaultik

# ─── REQUIRED ────────────────────────────────────────────────────────────────

# Age recipient public keys for encryption.
# Backups are encrypted to ALL listed recipients. Any one of the corresponding
# private keys can decrypt. Generate a keypair with:
#   age-keygen -o key.txt && grep 'public key' key.txt
age_recipients:
  - age1REPLACE_WITH_YOUR_PUBLIC_KEY

# Named snapshots. Each snapshot backs up one or more paths and can have its
# own exclude patterns in addition to the global excludes below.
#
# Exclude pattern semantics:
#   - Patterns starting with / are anchored to the snapshot path root
#     (e.g. "/Library/Caches" matches only ~/Library/Caches in a ~ snapshot)
#   - Patterns without a leading / match anywhere in the tree
#     (e.g. ".cache" matches any directory named .cache at any depth)
#   - Globs are supported: *, **, ?
snapshots:
  home:
    paths:
      - "~"
    exclude:
      # Trash, temp, and filesystem metadata
      - "/.Trash"
      - "/.Trashes"
      - "/.fseventsd"
      - "/.Spotlight-V100"
      - "/.TemporaryItems"
      - "/tmp"
      - "/.rnd"
      - ".DS_Store"
      # Caches and package manager state (rebuildable)
      - ".cache"
      - ".bundle"
      - "/.cpan/build"
      - "/.cpan/sources"
      - "/.gradle/caches"
      - "/.dropbox"
      - "/.minikube/cache"
      - "/.local/share/containers/podman/machine"
      - "/.persepolis"
      - "/Library/Caches"
      - "/Library/Logs"
      - "/Library/Cookies"
      - "/Library/Metadata"
      - "/Library/Suggestions"
      - "/Library/PubSub"
      - "/Library/Homebrew"
      - "/Library/Developer"
      - "/Library/Google/GoogleSoftwareUpdate"
      - "/Library/Preferences/Macromedia/Flash Player"
      - "/Library/Preferences/SDMHelpData"
      - "/Library/VoiceTrigger/SAT"
      # Language/toolchain package caches (rebuildable from registries)
      - "/.npm"
      - "/.cargo/registry"
      - "/.cargo/git"
      - "/.rustup/toolchains"
      - "/go/pkg/mod"
      - "/.m2/repository"
      - "/.vagrant.d/boxes"
      - "node_modules"
      - "__pycache__"
      - ".venv"
      # Virtual machine disk images (huge; remove these lines to back them up)
      - "/Parallels"
      - "/Virtual Machines.localized"
      - "/VirtualBox VMs"
      - "/.orbstack"
      - "/Library/Containers/com.utmapp.UTM"
      # Downloaded LLM models (huge, re-downloadable)
      - "/.ollama/models"
      - "/.lmstudio/models"
      # Cloud-synced storage. These are synced to a provider already, and on
      # modern macOS may contain dataless placeholder files that the backup
      # would force-download in full.
      - "/Library/CloudStorage"
      - "/Library/Mobile Documents"
      # Android SDK and emulator images (re-downloadable)
      - "/Library/Android/sdk"
      - "/.android/avd"
      # Cloud-synced or restorable-from-server data
      - "/Library/Mail"
      - "/Library/Mail Downloads"
      - "/Library/Safari"
      - "/Library/Application Support/Evernote"
      - "/Library/Application Support/MobileSync"
      - "/Library/Application Support/SyncServices"
      - "/Library/Application Support/protonmail/bridge/cache"
      - "/Library/Application Support/Syncthing/index-*"
      - "/Library/Syncthing/folders"
      - "/Documents/Dropbox/.dropbox.cache"
      # Large rebuildable app data (games, media caches, device backups)
      - "/Applications/Fortnite"
      - "/Documents/Steam Content"
      - "/Library/Application Support/Ableton"
      - "/Library/Application Support/CrossOver Games"
      - "/Library/Application Support/SecondLife/cache"
      - "/Library/Application Support/Steam/SteamApps"
      - "/Library/Containers/com.docker.docker"
      - "/Library/Group Containers/group.com.apple.secure-control-center-preferences"
      - "/Library/iTunes/iPad Software Updates"
      - "/Library/iTunes/iPhone Software Updates"
      - "/Movies/CacheClip"
      - "/Movies/ProxyMedia"
      - "/Music/iTunes/Album Artwork"
      - "/Pictures/iPod Photo Cache"

  # Third-party applications. OS-provided apps live in /System/Applications
  # on modern macOS and are never in /Applications, but Apple-installed
  # App Store apps (Safari, GarageBand, iWork, iMovie) are excluded since
  # they are re-downloadable.
  apps:
    paths:
      - /Applications
    exclude:
      - ".DS_Store"
      - "/Safari.app"
      - "/GarageBand.app"
      - "/iMovie.app"
      - "/Keynote.app"
      - "/Numbers.app"
      - "/Pages.app"
      - "/Xcode.app"
      - "/Spotify.app"
      - "/Steam.app"
      - "/VirtualBox.app"
      - "/Utilities/Adobe Installers"

# Storage backend (pick ONE of the three forms below).
#
# S3-compatible:
#   storage_url: "s3://mybucket/backups?endpoint=s3.example.com&region=us-east-1"
#   (also set s3.access_key_id and s3.secret_access_key below)
#
# Local filesystem:
#   storage_url: "file:///mnt/backups/vaultik"
#
# Rclone (requires rclone configured separately):
#   storage_url: "rclone://myremote/path/to/backups"
storage_url: ""

# ─── S3 CREDENTIALS (required for s3:// storage_url) ────────────────────────

# s3:
#   access_key_id: YOUR_ACCESS_KEY
#   secret_access_key: YOUR_SECRET_KEY
#   # region: us-east-1        # Default: us-east-1
#   # use_ssl: true            # Default: true
#   # part_size: 5MB           # Multipart upload part size. Default: 5MB

# ─── OPTIONAL ────────────────────────────────────────────────────────────────

# Global exclude patterns applied to ALL snapshots.
# Snapshot-specific excludes are additive.
# exclude:
#   - "*.log"
#   - "*.tmp"
#   - ".git"
#   - "node_modules"

# Average chunk size for content-defined chunking (FastCDC).
# Smaller = better deduplication but more metadata overhead.
# Accepts: 1MB, 10M, 64KB, etc.
# Default: 10MB
# chunk_size: 10MB

# Maximum blob size before splitting into a new blob.
# Accepts: 1GB, 10G, 500MB, etc.
# Default: 10GB
# blob_size_limit: 10GB

# Zstd compression level (1-19). Higher = better ratio but slower.
# Default: 3
# compression_level: 3

# Hostname used in snapshot IDs. Default: system hostname.
# hostname: myserver

# Path to the local SQLite index database.
# Default: the platform data directory, e.g.
#   macOS: ~/Library/Application Support/vaultik/index.sqlite
#   Linux: ~/.local/share/vaultik/index.sqlite
# index_path: /path/to/index.sqlite
`

// NewConfigCommand creates the config command group.
func NewConfigCommand() *cobra.Command {
	cmd := &cobra.Command{
		Use:   "config",
		Short: "Manage the configuration file",
		Long:  "Commands for creating, editing, and querying the vaultik config file.",
	}

	cmd.AddCommand(newConfigInitCommand())
	cmd.AddCommand(newConfigEditCommand())
	cmd.AddCommand(newConfigGetCommand())
	cmd.AddCommand(newConfigSetCommand())

	return cmd
}

// newConfigInitCommand creates the 'config init' subcommand.
func newConfigInitCommand() *cobra.Command {
	return &cobra.Command{
		Use:   "init",
		Short: "Write a default config file",
		Long: `Creates a default configuration file with commented explanations
for every setting. If a config file already exists at the target path,
the command refuses to overwrite it.

The config is written to the path from --config, $VAULTIK_CONFIG, or
the platform default config directory (e.g. ~/Library/Application Support/
on macOS, ~/.config/ on Linux, /etc/vaultik/ as root).`,
		Args: cobra.NoArgs,
		RunE: func(cmd *cobra.Command, args []string) error {
			path := configPathForInit()

			if _, err := os.Stat(path); err == nil {
				return fmt.Errorf("config file already exists: %s", path)
			}

			dir := filepath.Dir(path)
			if err := os.MkdirAll(dir, 0o755); err != nil {
				return fmt.Errorf("creating config directory %s: %w", dir, err)
			}

			if err := os.WriteFile(path, []byte(defaultConfigTemplate), 0o600); err != nil {
				return fmt.Errorf("writing config file: %w", err)
			}

			fmt.Printf("Config written to %s\n", path)
			fmt.Println("Edit it to set your age_recipients, snapshots, and storage_url.")
			return nil
		},
	}
}

// newConfigEditCommand creates the 'config edit' subcommand.
func newConfigEditCommand() *cobra.Command {
	return &cobra.Command{
		Use:   "edit",
		Short: "Open the config file in $EDITOR",
		Args:  cobra.NoArgs,
		RunE: func(cmd *cobra.Command, args []string) error {
			path, err := ResolveConfigPath()
			if err != nil {
				return err
			}

			editor := os.Getenv("EDITOR")
			if editor == "" {
				editor = "vi"
			}

			ed := exec.Command(editor, path)
			ed.Stdin = os.Stdin
			ed.Stdout = os.Stdout
			ed.Stderr = os.Stderr
			return ed.Run()
		},
	}
}

// newConfigGetCommand creates the 'config get' subcommand.
func newConfigGetCommand() *cobra.Command {
	return &cobra.Command{
		Use:   "get <key>",
		Short: "Print a config value by dotted path (e.g. s3.bucket)",
		Args:  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			path, err := ResolveConfigPath()
			if err != nil {
				return err
			}

			root, err := loadYAMLFile(path)
			if err != nil {
				return err
			}

			node, err := yamlPathGet(root, strings.Split(args[0], "."))
			if err != nil {
				return err
			}

			if node.Kind == yaml.ScalarNode {
				fmt.Println(node.Value)
				return nil
			}

			out, err := yaml.Marshal(node)
			if err != nil {
				return fmt.Errorf("marshaling value: %w", err)
			}
			fmt.Print(string(out))
			return nil
		},
	}
}

// newConfigSetCommand creates the 'config set' subcommand.
func newConfigSetCommand() *cobra.Command {
	return &cobra.Command{
		Use:   "set <key> <value>",
		Short: "Set a config value by dotted path (e.g. compression_level 5)",
		Long: `Sets a scalar config value addressed by dotted YAML path and writes
the file back, preserving comments and formatting. Intermediate maps
are created as needed.

Examples:
  vaultik config set compression_level 9
  vaultik config set s3.bucket mybucket
  vaultik config set storage_url "file:///mnt/backups"`,
		Args: cobra.ExactArgs(2),
		RunE: func(cmd *cobra.Command, args []string) error {
			path, err := ResolveConfigPath()
			if err != nil {
				return err
			}

			root, err := loadYAMLFile(path)
			if err != nil {
				return err
			}

			if err := yamlPathSet(root, strings.Split(args[0], "."), args[1]); err != nil {
				return err
			}

			out, err := yaml.Marshal(root)
			if err != nil {
				return fmt.Errorf("marshaling config: %w", err)
			}

			mode := os.FileMode(0o600)
			if info, err := os.Stat(path); err == nil {
				mode = info.Mode().Perm()
			}

			if err := os.WriteFile(path, out, mode); err != nil {
				return fmt.Errorf("writing config file: %w", err)
			}

			fmt.Printf("%s = %s\n", args[0], args[1])
			return nil
		},
	}
}

// loadYAMLFile parses a YAML file into a yaml.Node document tree,
// which preserves comments and ordering for round-tripping.
func loadYAMLFile(path string) (*yaml.Node, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("reading config file: %w", err)
	}

	var root yaml.Node
	if err := yaml.Unmarshal(data, &root); err != nil {
		return nil, fmt.Errorf("parsing config file: %w", err)
	}

	// An empty file yields a zero node; normalize to an empty mapping document.
	if root.Kind == 0 {
		root = yaml.Node{
			Kind:    yaml.DocumentNode,
			Content: []*yaml.Node{{Kind: yaml.MappingNode}},
		}
	}

	return &root, nil
}

// yamlPathGet navigates a dotted key path through mapping and sequence
// nodes and returns the value node. Numeric path components index into
// sequences (e.g. "age_recipients.0").
func yamlPathGet(root *yaml.Node, keys []string) (*yaml.Node, error) {
	node := root
	if node.Kind == yaml.DocumentNode {
		if len(node.Content) == 0 {
			return nil, fmt.Errorf("empty config file")
		}
		node = node.Content[0]
	}

	for i, key := range keys {
		switch node.Kind {
		case yaml.MappingNode:
			found := false
			for j := 0; j+1 < len(node.Content); j += 2 {
				if node.Content[j].Value == key {
					node = node.Content[j+1]
					found = true
					break
				}
			}
			if !found {
				return nil, fmt.Errorf("key not found: %s", strings.Join(keys[:i+1], "."))
			}
		case yaml.SequenceNode:
			idx, err := strconv.Atoi(key)
			if err != nil {
				return nil, fmt.Errorf("key %q is a list; use a numeric index", strings.Join(keys[:i], "."))
			}
			if idx < 0 || idx >= len(node.Content) {
				return nil, fmt.Errorf("index %d out of range for %s (len %d)", idx, strings.Join(keys[:i], "."), len(node.Content))
			}
			node = node.Content[idx]
		default:
			return nil, fmt.Errorf("key %q is not a map or list", strings.Join(keys[:i], "."))
		}
	}

	return node, nil
}

// yamlPathSet navigates a dotted key path, creating intermediate maps as
// needed, and sets the final key to the given scalar value. Numeric path
// components index into sequences; an index equal to the sequence length
// appends a new element (e.g. "age_recipients.1" on a 1-element list).
func yamlPathSet(root *yaml.Node, keys []string, value string) error {
	node := root
	if node.Kind == yaml.DocumentNode {
		if len(node.Content) == 0 {
			node.Content = []*yaml.Node{{Kind: yaml.MappingNode}}
		}
		node = node.Content[0]
	}

	for i, key := range keys {
		last := i == len(keys)-1

		switch node.Kind {
		case yaml.MappingNode:
			var valueNode *yaml.Node
			for j := 0; j+1 < len(node.Content); j += 2 {
				if node.Content[j].Value == key {
					valueNode = node.Content[j+1]
					break
				}
			}

			if valueNode == nil {
				keyNode := &yaml.Node{Kind: yaml.ScalarNode, Value: key}
				valueNode = &yaml.Node{Kind: yaml.MappingNode}
				if last {
					valueNode = &yaml.Node{Kind: yaml.ScalarNode, Value: value}
				}
				node.Content = append(node.Content, keyNode, valueNode)
			} else if last {
				setScalar(valueNode, value)
			}

			node = valueNode

		case yaml.SequenceNode:
			idx, err := strconv.Atoi(key)
			if err != nil {
				return fmt.Errorf("key %q is a list; use a numeric index", strings.Join(keys[:i], "."))
			}
			if idx < 0 || idx > len(node.Content) {
				return fmt.Errorf("index %d out of range for %s (len %d)", idx, strings.Join(keys[:i], "."), len(node.Content))
			}
			if idx == len(node.Content) {
				newNode := &yaml.Node{Kind: yaml.MappingNode}
				if last {
					newNode = &yaml.Node{Kind: yaml.ScalarNode, Value: value}
				}
				node.Content = append(node.Content, newNode)
			} else if last {
				setScalar(node.Content[idx], value)
			}
			node = node.Content[idx]

		default:
			return fmt.Errorf("key %q is not a map or list", strings.Join(keys[:i], "."))
		}
	}

	return nil
}

// setScalar overwrites a node in place with a plain scalar value.
func setScalar(n *yaml.Node, value string) {
	n.Kind = yaml.ScalarNode
	n.Tag = ""
	n.Value = value
	n.Content = nil
	n.Style = 0
}

// configPathForInit returns the config path to write, checking --config flag,
// VAULTIK_CONFIG env, and the platform default.
func configPathForInit() string {
	if rootFlags.ConfigPath != "" {
		return rootFlags.ConfigPath
	}
	if envPath := os.Getenv("VAULTIK_CONFIG"); envPath != "" {
		return envPath
	}
	return DefaultConfigPath()
}