package hook

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

// 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, 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 {
	configDir, err := os.UserConfigDir()
	if err != nil {
		configDir = filepath.Join(os.Getenv("HOME"), ".config")
	}
	return filepath.Join(configDir, "fish", "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
	return nil
}

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 {
		fmt.Fprintf(&b, "alias %s='netssh %s'\n", e.Name, e.Host)
	}
	return os.WriteFile(p, []byte(b.String()), 0o644)
}

func writeFishAliasFile(entries []AliasEntry) {
	configDir, err := os.UserConfigDir()
	if err != nil {
		return
	}
	// Only write if fish is configured on this system.
	if _, err := os.Stat(filepath.Join(configDir, "fish")); 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 {
		fmt.Fprintf(&b, "alias %s 'netssh %s'\n", e.Name, e.Host)
	}
	os.WriteFile(p, []byte(b.String()), 0o644) //nolint:errcheck
}