package config

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

func envWritebackEnabled() bool {
	v := strings.ToLower(strings.TrimSpace(os.Getenv("DS2API_ENV_WRITEBACK")))
	return v == "1" || v == "true" || v == "yes" || v == "on"
}

func (s *Store) IsEnvWritebackEnabled() bool {
	return envWritebackEnabled()
}

func (s *Store) HasEnvConfigSource() bool {
	rawCfg := strings.TrimSpace(os.Getenv("DS2API_CONFIG_JSON"))
	return rawCfg != ""
}

func (s *Store) ConfigPath() string {
	return s.path
}

func writeConfigFile(path string, cfg Config) error {
	persistCfg := cfg.Clone()
	persistCfg.ClearAccountTokens()
	b, err := json.MarshalIndent(persistCfg, "", "  ")
	if err != nil {
		return err
	}
	return writeConfigBytes(path, b)
}

// overwriteFile writes data to path. If the write fails due to permission
// issues (common on HuggingFace Spaces where the file may be owned by root),
// it removes the old file and retries.
func overwriteFile(path string, b []byte, perm os.FileMode) error {
	if err := os.WriteFile(path, b, perm); err != nil {
		if removeErr := os.Remove(path); removeErr == nil {
			return os.WriteFile(path, b, perm)
		}
		return err
	}
	return nil
}

func writeConfigBytes(path string, b []byte) error {
	dir := filepath.Dir(path)
	if dir == "." || dir == "" {
		return overwriteFile(path, b, 0o644)
	}
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return fmt.Errorf("mkdir config dir: %w", err)
	}
	// Write to a temp file first, then rename atomically to avoid
	// leaving a corrupted/truncated config on crash or disk-full.
	tmp, err := os.CreateTemp(dir, ".ds2api-config-*")
	if err != nil {
		return fmt.Errorf("create temp config file: %w", err)
	}
	tmpName := tmp.Name()
	wrote := false
	defer func() {
		if !wrote {
			_ = tmp.Close()
			_ = os.Remove(tmpName)
		}
	}()
	if _, err := tmp.Write(b); err != nil {
		return fmt.Errorf("write temp config: %w", err)
	}
	if err := tmp.Sync(); err != nil {
		return fmt.Errorf("sync temp config: %w", err)
	}
	if err := tmp.Close(); err != nil {
		return fmt.Errorf("close temp config: %w", err)
	}
	wrote = true
	if err := os.Rename(tmpName, path); err != nil {
		// Rename may fail because the existing file has wrong ownership/permissions
		// (common on HuggingFace Spaces where /data/config.json may be owned by root).
		// Try removing the old file and renaming again.
		if removeErr := os.Remove(path); removeErr == nil {
			if renameErr := os.Rename(tmpName, path); renameErr == nil {
				return nil
			}
		}
		// Rename still failing (e.g. cross-filesystem); fall back to direct write.
		_ = os.Remove(tmpName)
		return overwriteFile(path, b, 0o644)
	}
	return nil
}