package config

import (
	"bytes"
	"fmt"
	"os"

	"gopkg.in/yaml.v3"
)

// Load reads and decodes the file at path. A missing file is not an error:
// it returns a zero-valued *File so the tool remains usable purely from
// flags/env (see the package doc). Unknown YAML keys are a hard error so
// typos in a hand-edited config surface immediately instead of being
// silently ignored.
func Load(path string) (*File, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			return &File{Version: SchemaVersion}, nil
		}
		return nil, fmt.Errorf("reading config %q: %w", path, err)
	}

	var f File
	dec := yaml.NewDecoder(bytes.NewReader(data))
	dec.KnownFields(true)
	if err := dec.Decode(&f); err != nil {
		return nil, fmt.Errorf("parsing config %q: %w", path, err)
	}

	if f.Version == 0 {
		f.Version = SchemaVersion
	}
	if f.Version != SchemaVersion {
		return nil, fmt.Errorf("config %q has version %d, vault-tui supports version %d", path, f.Version, SchemaVersion)
	}
	for name, p := range f.Profiles {
		if p != nil && p.Token.Value != "" {
			fmt.Fprintf(os.Stderr, "warning: profile %q sets token.value directly in the config file; prefer VAULT_TOKEN or token.file\n", name)
		}
	}
	return &f, nil
}

// Save writes f to path as YAML, creating parent directories as needed.
// The file is written with 0600 permissions since profiles may carry
// TLS key paths and (discouraged but supported) inline token values.
func Save(path string, f *File) error {
	if err := os.MkdirAll(dirOf(path), 0o700); err != nil {
		return fmt.Errorf("creating config directory: %w", err)
	}
	var buf bytes.Buffer
	enc := yaml.NewEncoder(&buf)
	enc.SetIndent(2)
	if err := enc.Encode(f); err != nil {
		return fmt.Errorf("encoding config: %w", err)
	}
	if err := enc.Close(); err != nil {
		return err
	}
	return os.WriteFile(path, buf.Bytes(), 0o600)
}

func dirOf(path string) string {
	for i := len(path) - 1; i >= 0; i-- {
		if path[i] == '/' {
			return path[:i]
		}
	}
	return "."
}

// Exists reports whether a config file is present at path.
func Exists(path string) bool {
	_, err := os.Stat(path)
	return err == nil
}