package ui

import (
	"errors"
	"fmt"
	"strings"

	"gitea.lab.audasmedia.com.au/sam/artemis_control/internal/adb"
)

// ErrLocked is returned when a secure keyguard is showing. Artemis never tries
// to get past it: no PIN, pattern or password is stored, read or typed
// (AGENTS.md section 13 Q2).
var ErrLocked = errors.New("phone is locked; unlock it and retry")

// KeyguardState reports whether the lock screen is showing and, separately,
// whether the device has a secure lock (PIN, pattern or password) at all.
//
// The two are independent: a phone with no PIN still shows a keyguard when it
// wakes, but that one may be dismissed. A secure one may not.
func KeyguardState(r *adb.Runner) (showing bool, secure bool, err error) {
	dump, err := r.Shell("dumpsys window")
	if err != nil {
		return false, false, fmt.Errorf("read window state: %w", err)
	}
	showing, err = keyguardShowing(dump)
	if err != nil {
		return false, false, err
	}
	secure, err = userHasSecureLock(r)
	if err != nil {
		return false, false, err
	}
	return showing, secure, nil
}

// keyguardShowing parses `dumpsys window` for the KeyguardServiceDelegate
// block. An unparsable dump is an error: guessing here would mean acting on a
// phone whose lock state is unknown.
func keyguardShowing(dump string) (bool, error) {
	showing := false
	sawDelegate := false
	sawShowing := false
	inDelegate := false

	for _, raw := range strings.Split(dump, "\n") {
		line := strings.TrimSpace(raw)
		switch {
		case strings.HasPrefix(line, "KeyguardServiceDelegate"):
			inDelegate, sawDelegate = true, true
			continue
		case strings.HasPrefix(line, "isKeyguardShowing="):
			if strings.TrimPrefix(line, "isKeyguardShowing=") == "true" {
				showing = true
			}
			continue
		}
		if !inDelegate {
			continue
		}
		// The delegate block is a flat list of key=value lines.
		if !strings.Contains(line, "=") {
			inDelegate = false
			continue
		}
		if strings.HasPrefix(line, "showing=") {
			showing = strings.TrimPrefix(line, "showing=") == "true"
			sawShowing = true
		}
	}

	if !sawDelegate || !sawShowing {
		return false, fmt.Errorf("could not read the keyguard state from dumpsys window")
	}
	return showing, nil
}

// userHasSecureLock asks the lock settings service whether the current user has
// a secure lock screen. It never asks for or handles the credential itself.
func userHasSecureLock(r *adb.Runner) (bool, error) {
	out, err := r.Shell("cmd lock_settings is-user-secure")
	if err != nil {
		return false, fmt.Errorf("read lock state: %w", err)
	}
	switch strings.TrimSpace(out) {
	case "true":
		return true, nil
	case "false":
		return false, nil
	}
	return false, fmt.Errorf("unexpected lock state %q from cmd lock_settings is-user-secure", strings.TrimSpace(out))
}

// RequireUnlocked refuses to act while a secure keyguard is showing.
//
// A non-secure keyguard (the phone has no PIN at all) is dismissed, because
// that screen guards nothing. A secure one is left alone: Artemis stops and
// says so.
func RequireUnlocked(r *adb.Runner) error {
	showing, secure, err := KeyguardState(r)
	if err != nil {
		return fmt.Errorf("cannot confirm the phone is unlocked: %w", err)
	}
	if !showing {
		return nil
	}
	if secure {
		return ErrLocked
	}
	if _, err := r.Shell("wm dismiss-keyguard"); err != nil {
		return fmt.Errorf("dismiss the non-secure keyguard: %w", err)
	}
	return nil
}