// Package paths mirrors behavision/paths.py.
//
// The two processes must agree on where state lives or they will quietly use
// different databases: the engine would write footfall into one file while the
// agent reads another and reports an empty store. The rule is the same on both
// sides — BEHAVISION_DATA_DIR wins, then %PROGRAMDATA%\Behavision on Windows —
// and `behavision paths` prints the engine's answer so the two can be compared
// on a real machine rather than assumed equal.
package paths

import (
	"os"
	"path/filepath"
	"runtime"
)

const AppName = "Behavision"

// StateRoot is the writable root: database, logs, spool, agent config.
func StateRoot() string {
	if v := os.Getenv("BEHAVISION_DATA_DIR"); v != "" {
		if abs, err := filepath.Abs(v); err == nil {
			return abs
		}
		return v
	}
	if runtime.GOOS == "windows" {
		base := os.Getenv("PROGRAMDATA")
		if base == "" {
			base = `C:\ProgramData`
		}
		return filepath.Join(base, AppName)
	}
	home, err := os.UserHomeDir()
	if err != nil {
		return "."
	}
	if runtime.GOOS == "darwin" {
		return filepath.Join(home, "Library", "Application Support", AppName)
	}
	if v := os.Getenv("XDG_DATA_HOME"); v != "" {
		return filepath.Join(v, "behavision")
	}
	return filepath.Join(home, ".local", "share", "behavision")
}

// InstallRoot is the directory holding this executable.
func InstallRoot() string {
	exe, err := os.Executable()
	if err != nil {
		return "."
	}
	if resolved, err := filepath.EvalSymlinks(exe); err == nil {
		exe = resolved
	}
	return filepath.Dir(exe)
}

func AgentConfig() string { return filepath.Join(StateRoot(), "agent.json") }
func SpoolDir() string    { return filepath.Join(StateRoot(), "spool") }
func EngineLog() string   { return filepath.Join(StateRoot(), "engine.log") }

// APICredentials is the file the engine writes when it generates its own
// Basic credentials. The agent reads it rather than storing a second copy,
// so a regenerated credential does not silently break the tray.
func APICredentials() string {
	return filepath.Join(StateRoot(), "data", "api_credentials.txt")
}

// EnsureState creates the writable tree. Called before anything opens a file
// under it, so a first run on a fresh machine does not fail on a missing dir.
func EnsureState() error {
	for _, d := range []string{StateRoot(), SpoolDir()} {
		if err := os.MkdirAll(d, 0o700); err != nil {
			return err
		}
	}
	return nil
}