package org.julianfamily.keepassgo;

import android.accessibilityservice.AccessibilityService;
import android.os.Build;
import android.os.Bundle;
import android.util.Log;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityNodeInfo;

import java.util.ArrayList;
import java.util.List;

public final class KeePassGOAccessibilityService extends AccessibilityService {
    private static final String TAG = "KeePassGOA11y";
    private String lastFilledSignature = "";

    @Override
    public void onAccessibilityEvent(AccessibilityEvent event) {
        try {
            AccessibilityNodeInfo root = getRootInActiveWindow();
            if (root == null) {
                return;
            }
            ChromeForm form = inspectWindow(root);
            if (form == null || form.passwordField == null) {
                return;
            }
            AutofillCacheStore.Entry entry = AutofillCacheStore.findBestMatch(this, form.matchTarget);
            if (entry == null) {
                Log.i(TAG, "no accessibility-fill match for " + form.matchTarget);
                return;
            }

            String signature = form.matchTarget + "|" + entry.username + "|" + nodeKey(form.passwordField);
            if (signature.equals(lastFilledSignature)) {
                return;
            }

            boolean filled = false;
            if (form.usernameField != null) {
                filled |= setNodeText(form.usernameField, entry.username);
            }
            filled |= setNodeText(form.passwordField, entry.password);
            if (filled) {
                lastFilledSignature = signature;
                Log.i(TAG, "filled login form for " + form.matchTarget + " with " + entry.username);
            }
        } catch (Exception err) {
            Log.e(TAG, "accessibility fill failed", err);
        }
    }

    @Override
    public void onInterrupt() {
        Log.i(TAG, "accessibility service interrupted");
    }

    private static ChromeForm inspectWindow(AccessibilityNodeInfo root) {
        List<AccessibilityNodeInfo> editables = new ArrayList<>();
        ChromeForm form = new ChromeForm();
        walk(root, editables, form);
        if (form.matchTarget.isEmpty()) {
            return null;
        }
        if (form.passwordField == null) {
            for (AccessibilityNodeInfo node : editables) {
                if (isPasswordNode(node)) {
                    form.passwordField = node;
                    break;
                }
            }
        }
        if (form.usernameField == null && form.passwordField != null) {
            for (AccessibilityNodeInfo node : editables) {
                if (node.equals(form.passwordField)) {
                    continue;
                }
                if (isUsernameNode(node)) {
                    form.usernameField = node;
                    break;
                }
            }
            if (form.usernameField == null) {
                for (AccessibilityNodeInfo node : editables) {
                    if (node.equals(form.passwordField)) {
                        continue;
                    }
                    form.usernameField = node;
                    break;
                }
            }
        }
        return form;
    }

    private static void walk(
            AccessibilityNodeInfo node,
            List<AccessibilityNodeInfo> editables,
            ChromeForm form
    ) {
        if (node == null) {
            return;
        }
        CharSequence viewID = node.getViewIdResourceName();
        if (viewID != null && viewID.toString().endsWith(":id/url_bar")) {
            CharSequence text = node.getText();
            if (text != null) {
                form.webDomain = text.toString().trim();
            }
        }
        if (form.packageName.isEmpty()) {
            CharSequence packageName = node.getPackageName();
            if (packageName != null) {
                form.packageName = packageName.toString().trim();
            }
        }
        if (node.isEditable()) {
            editables.add(node);
            if (form.passwordField == null && isPasswordNode(node)) {
                form.passwordField = node;
            } else if (form.usernameField == null && isUsernameNode(node)) {
                form.usernameField = node;
            }
        }
        for (int i = 0; i < node.getChildCount(); i++) {
            AccessibilityNodeInfo child = node.getChild(i);
            if (child != null) {
                walk(child, editables, form);
            }
        }
        form.matchTarget = AutofillFallbackTarget.resolve(form.packageName, form.webDomain);
    }

    private static boolean isPasswordNode(AccessibilityNodeInfo node) {
        if (node.isPassword()) {
            return true;
        }
        return nodeMatches(node, "password");
    }

    private static boolean isUsernameNode(AccessibilityNodeInfo node) {
        if (isPasswordNode(node)) {
            return false;
        }
        return nodeMatches(node, "username")
                || nodeMatches(node, "email")
                || nodeMatches(node, "login")
                || nodeMatches(node, "user");
    }

    private static boolean nodeMatches(AccessibilityNodeInfo node, String term) {
        String lowerTerm = term.toLowerCase();
        return containsLower(node.getHintText(), lowerTerm)
                || containsLower(node.getText(), lowerTerm)
                || containsLower(node.getContentDescription(), lowerTerm)
                || containsLower(node.getViewIdResourceName(), lowerTerm)
                || containsLower(node.getPaneTitle(), lowerTerm);
    }

    private static boolean containsLower(CharSequence value, String term) {
        return value != null && value.toString().toLowerCase().contains(term);
    }

    private static boolean setNodeText(AccessibilityNodeInfo node, String value) {
        if (node == null || !node.isEditable() || value == null) {
            return false;
        }
        Bundle args = new Bundle();
        args.putCharSequence(
                AccessibilityNodeInfo.ACTION_ARGUMENT_SET_TEXT_CHARSEQUENCE,
                value
        );
        return node.performAction(AccessibilityNodeInfo.ACTION_SET_TEXT, args);
    }

    private static String nodeKey(AccessibilityNodeInfo node) {
        CharSequence viewID = node.getViewIdResourceName();
        if (viewID != null) {
            return viewID.toString();
        }
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
            return String.valueOf(node.getUniqueId());
        }
        CharSequence hint = node.getHintText();
        if (hint != null) {
            return hint.toString();
        }
        return String.valueOf(node.hashCode());
    }

    private static final class ChromeForm {
        String packageName = "";
        String webDomain = "";
        String matchTarget = "";
        AccessibilityNodeInfo usernameField;
        AccessibilityNodeInfo passwordField;
    }
}