package hook

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

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

const completionMarker = "# netssh command alias completion — generated automatically"

// SyncCommandCompletion installs lazy loaders for the configured command alias.
// The loaders obtain the canonical completion from the current netssh binary,
// so aliases configured by the wizard work without a separate completion install.
func SyncCommandCompletion(alias string) error {
	if err := config.ValidateCommandAlias(alias); err != nil {
		return err
	}
	statePath := filepath.Join(filepath.Dir(AliasesPath()), "completion_alias")
	data, err := os.ReadFile(statePath)
	if err != nil && !os.IsNotExist(err) {
		return err
	}
	previous := strings.TrimSpace(string(data))
	if err := config.ValidateCommandAlias(previous); err != nil {
		return fmt.Errorf("invalid completion alias state: %w", err)
	}
	if alias == "" && previous == "" {
		return nil
	}

	for _, shell := range []string{"bash", "zsh", "fish"} {
		if previous != "" && previous != alias {
			path := commandCompletionPath(shell, previous)
			data, err := os.ReadFile(path)
			if err != nil && !os.IsNotExist(err) {
				return err
			}
			// Only delete files owned by netssh; preserve any user replacements.
			if strings.HasPrefix(string(data), completionMarker+"\n") || strings.HasPrefix(string(data), "#compdef "+previous+"\n"+completionMarker+"\n") {
				if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
					return err
				}
			}
		}
		if alias == "" {
			continue
		}
		if shell == "fish" {
			if _, err := os.Stat(FishConfigDir()); os.IsNotExist(err) {
				continue
			} else if err != nil {
				return err
			}
		}
		path := commandCompletionPath(shell, alias)
		script := commandCompletionScript(shell, alias)
		existing, err := os.ReadFile(path)
		if err != nil && !os.IsNotExist(err) {
			return err
		}
		if string(existing) == script {
			continue
		}
		if err := storage.WriteFile(path, []byte(script), 0o644); err != nil {
			return fmt.Errorf("writing %s alias completion: %w", shell, err)
		}
	}
	if alias == "" {
		if err := os.Remove(statePath); err != nil && !os.IsNotExist(err) {
			return err
		}
		return nil
	}
	return storage.WriteFile(statePath, []byte(alias+"\n"), 0o600)
}

func commandCompletionPath(shell, alias string) string {
	switch shell {
	case "bash":
		return filepath.Join(os.Getenv("HOME"), ".local", "share", "bash-completion", "completions", alias)
	case "zsh":
		return filepath.Join(ZshFuncDir(), "_"+alias)
	default:
		return filepath.Join(FishConfigDir(), "completions", alias+".fish")
	}
}

func commandCompletionScript(shell, alias string) string {
	switch shell {
	case "bash":
		return fmt.Sprintf(`%s
source <(netssh completion bash)
if [[ $(type -t compopt) == builtin ]]; then
    complete -o default -F __start_netssh %s
else
    complete -o default -o nospace -F __start_netssh %s
fi
`, completionMarker, alias, alias)
	case "zsh":
		return fmt.Sprintf(`#compdef %s
%s
source <(netssh completion zsh)
compdef _netssh %s
_netssh "$@"
`, alias, completionMarker, alias)
	default:
		return fmt.Sprintf(`%s
netssh completion fish | source
complete --command %s --wraps netssh
`, completionMarker, alias)
	}
}