package hook

import (
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strings"

	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/cache"
	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/config"
	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/shortcuts"
	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/storage"
)

// AliasEntry holds a single shell alias mapping.
type AliasEntry struct {
	Name string // short alias name (e.g. "web01")
	Host string // canonical NetBox hostname (e.g. "web01.example.com")
}

// AliasesPath returns the path for the bash/zsh aliases file.
func AliasesPath() string {
	cacheDir := os.Getenv("XDG_CACHE_HOME")
	if cacheDir == "" {
		var err error
		cacheDir, err = os.UserCacheDir()
		if err != nil {
			cacheDir = filepath.Join(os.Getenv("HOME"), ".cache")
		}
	}
	return filepath.Join(cacheDir, "netssh", "aliases.sh")
}

// FishAliasesPath returns the path for the fish conf.d aliases file.
// Fish auto-sources every file in conf.d, so no explicit source line is needed.
func FishAliasesPath() string {
	return filepath.Join(FishConfigDir(), "conf.d", "netssh.fish")
}

// WriteAliasFiles writes alias definitions to disk for all supported shells.
//
// The bash/zsh file (~/.cache/netssh/aliases.sh) is always written.
// The fish file (~/.config/fish/conf.d/netssh.fish) is written only when
// ~/.config/fish/ already exists (i.e. fish is configured on this system).
func WriteAliasFiles(entries []AliasEntry) error {
	if err := writeShAliasFile(entries); err != nil {
		return err
	}
	writeFishAliasFile(entries) // best-effort — never blocks the caller on failure
	alias := ""
	for _, entry := range entries {
		if entry.Host == "" {
			alias = entry.Name
			break
		}
	}
	return SyncCommandCompletion(alias)
}

func writeShAliasFile(entries []AliasEntry) error {
	p := AliasesPath()
	if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
		return fmt.Errorf("creating aliases dir: %w", err)
	}
	var b strings.Builder
	b.WriteString("# netssh aliases — generated automatically, do not edit\n")
	b.WriteString("# Regenerated on every shell start and after 'netssh cache refresh'.\n")
	for _, e := range entries {
		b.WriteString(e.Definition("bash") + "\n")
	}
	return storage.WriteFile(p, []byte(b.String()), 0o600)
}

func writeFishAliasFile(entries []AliasEntry) {
	// Only write if fish is configured on this system.
	if _, err := os.Stat(FishConfigDir()); err != nil {
		return
	}
	p := FishAliasesPath()
	if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
		return
	}
	var b strings.Builder
	b.WriteString("# netssh aliases — generated automatically, do not edit\n")
	b.WriteString("# Regenerated on every shell start and after 'netssh cache refresh'.\n")
	for _, e := range entries {
		b.WriteString(e.Definition("fish") + "\n")
	}
	storage.WriteFile(p, []byte(b.String()), 0o600) //nolint:errcheck
}

// Empty Host represents an alias for the netssh command itself.
func (e AliasEntry) Definition(shell string) string {
	command := "netssh"
	if e.Host != "" {
		host := e.Host
		if !regexp.MustCompile(`^[a-zA-Z0-9_.:-]+$`).MatchString(host) {
			host = shellQuote(host, shell)
		}
		command += " " + host
	}
	if shell == "fish" {
		return fmt.Sprintf("alias %s %s", e.Name, shellQuote(command, shell))
	}
	return fmt.Sprintf("alias %s=%s", e.Name, shellQuote(command, shell))
}

func shellQuote(value, shell string) string {
	if shell == "fish" {
		value = strings.ReplaceAll(value, `\`, `\\`)
		return "'" + strings.ReplaceAll(value, "'", `\'`) + "'"
	}
	return "'" + strings.ReplaceAll(value, "'", `'\''`) + "'"
}

// BuildAliasEntries gives the configured command alias priority over host aliases.
func BuildAliasEntries(entries []cache.Entry, cfg config.Config) []AliasEntry {
	sort.Slice(entries, func(i, j int) bool { return entries[i].Name < entries[j].Name })
	seen := map[string]bool{"netssh": true}
	var out []AliasEntry
	if cfg.Shell.Alias != "" && config.ValidateCommandAlias(cfg.Shell.Alias) == nil {
		seen[cfg.Shell.Alias] = true
		out = append(out, AliasEntry{Name: cfg.Shell.Alias})
	}
	for _, e := range entries {
		name := shortcuts.AliasName(e.Name, cfg.Shortcuts)
		if seen[name] || name == "" || !regexp.MustCompile(`^[a-zA-Z_][a-zA-Z0-9_-]*$`).MatchString(name) {
			continue
		}
		seen[name] = true
		out = append(out, AliasEntry{Name: name, Host: e.Name})
	}
	return out
}

// FishConfigDir follows fish's XDG layout on both Linux and macOS.
func FishConfigDir() string {
	dir := os.Getenv("XDG_CONFIG_HOME")
	if dir == "" {
		dir = filepath.Join(os.Getenv("HOME"), ".config")
	}
	return filepath.Join(dir, "fish")
}