package org.openautonomousconnection.luascript.fx;

import javafx.scene.web.WebEngine;

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;
import java.util.function.Supplier;

/**
 * Shared utilities for WebEngine JS bridging.
 */
public final class FxWebBridge {

    private FxWebBridge() {
    }

    /**
     * Ensures JavaScript is enabled for the engine.
     *
     * @param engine engine
     */
    public static void ensureJsEnabled(WebEngine engine) {
        Objects.requireNonNull(engine, "engine");
        if (!engine.isJavaScriptEnabled()) {
            engine.setJavaScriptEnabled(true);
        }
    }

    /**
     * Executes bridge code with JavaScript temporarily enabled.
     *
     * @param engine engine
     * @param action action
     */
    public static void runWithJs(WebEngine engine, Runnable action) {
        Objects.requireNonNull(action, "action");
        callWithJs(engine, () -> {
            action.run();
            return null;
        });
    }

    /**
     * Executes bridge code with JavaScript temporarily enabled and restores the prior state.
     *
     * @param engine engine
     * @param action action
     * @param <T> result type
     * @return action result
     */
    public static <T> T callWithJs(WebEngine engine, Supplier<T> action) {
        Objects.requireNonNull(engine, "engine");
        Objects.requireNonNull(action, "action");

        boolean enabledBefore = engine.isJavaScriptEnabled();
        if (!enabledBefore) {
            engine.setJavaScriptEnabled(true);
        }
        try {
            return action.get();
        } finally {
            if (!enabledBefore) {
                engine.setJavaScriptEnabled(false);
            }
        }
    }

    /**
     * Converts a Java value into a safe JavaScript literal.
     *
     * <p>Supported: null, String, Boolean, Number (finite).</p>
     *
     * @param v value
     * @return JS literal
     */
    public static String toJsLiteral(Object v) {
        if (v == null) return "null";

        if (v instanceof String s) {
            return "'" + escapeJsSingleQuotedString(s) + "'";
        }

        if (v instanceof Boolean b) {
            return b ? "true" : "false";
        }

        if (v instanceof Number n) {
            double d = n.doubleValue();
            if (!Double.isFinite(d)) {
                throw new IllegalArgumentException("Non-finite number is not supported for JS literal: " + d);
            }
            return Double.toString(d);
        }

        throw new IllegalArgumentException("Unsupported value type for JS literal: " + v.getClass().getName());
    }

    /**
     * Builds a JavaScript array literal from Java values.
     *
     * @param values values
     * @return array literal
     */
    public static String toJsArrayLiteral(Object[] values) {
        if (values == null || values.length == 0) return "[]";
        StringBuilder sb = new StringBuilder();
        sb.append('[');
        for (int i = 0; i < values.length; i++) {
            if (i > 0) sb.append(',');
            sb.append(toJsLiteral(values[i]));
        }
        sb.append(']');
        return sb.toString();
    }

    /**
     * Restricts input to a plain JavaScript identifier (prevents injection).
     *
     * @param s     value
     * @param label label
     * @return identifier
     */
    public static String requireJsIdentifier(String s, String label) {
        if (s == null) throw new IllegalArgumentException(label + " is null");
        String v = s.trim();
        if (v.isEmpty()) throw new IllegalArgumentException(label + " is blank");
        if (!v.matches("^[A-Za-z_$][A-Za-z0-9_$]*$")) {
            throw new IllegalArgumentException(label + " must be a JS identifier: " + v);
        }
        return v;
    }

    /**
     * Normalizes alignment options for scrollIntoView.
     *
     * @param align input
     * @return normalized
     */
    public static String normalizeAlign(String align) {
        if (align == null) return "nearest";
        String a = align.trim().toLowerCase(Locale.ROOT);
        return switch (a) {
            case "start", "center", "end", "nearest" -> a;
            default -> "nearest";
        };
    }

    /**
     * Converts a JS array-like object into a Java string list.
     *
     * @param jsValue raw JS value
     * @return list of string values
     */
    public static List<String> toStringList(Object jsValue) {
        if (jsValue == null) return List.of();
        if (jsValue instanceof List<?> list) {
            List<String> out = new ArrayList<>(list.size());
            for (Object value : list) out.add(value == null ? null : String.valueOf(value));
            return out;
        }

        try {
            Class<?> jsObj = Class.forName("netscape.javascript.JSObject");
            if (jsObj.isInstance(jsValue)) {
                Object lenObj = jsObj.getMethod("getMember", String.class).invoke(jsValue, "length");
                int len = Integer.parseInt(String.valueOf(lenObj));
                List<String> out = new ArrayList<>(len);
                for (int i = 0; i < len; i++) {
                    Object value = jsObj.getMethod("getSlot", int.class).invoke(jsValue, i);
                    out.add(value == null ? null : String.valueOf(value));
                }
                return out;
            }
        } catch (Exception ignored) {
            // best-effort fallback below
        }

        return List.of(String.valueOf(jsValue));
    }

    /**
     * Converts a JS object into a Java string-object map when possible.
     *
     * @param jsValue raw JS value
     * @return mapped values
     */
    public static Map<String, Object> toStringObjectMap(Object jsValue) {
        if (jsValue == null) return Map.of();
        if (jsValue instanceof Map<?, ?> map) {
            Map<String, Object> out = new LinkedHashMap<>();
            for (Map.Entry<?, ?> entry : map.entrySet()) {
                if (entry.getKey() == null) continue;
                out.put(String.valueOf(entry.getKey()), entry.getValue());
            }
            return out;
        }

        return Map.of("value", jsValue);
    }

    private static String escapeJsSingleQuotedString(String s) {
        if (s == null || s.isEmpty()) return "";
        StringBuilder out = new StringBuilder(s.length() + 16);
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            switch (c) {
                case '\'' -> out.append("\\'");
                case '\\' -> out.append("\\\\");
                case '\n' -> out.append("\\n");
                case '\r' -> out.append("\\r");
                case '\t' -> out.append("\\t");
                case '\u0000' -> out.append("\\0");
                case '\u2028' -> out.append("\\u2028");
                case '\u2029' -> out.append("\\u2029");
                default -> {
                    if (c < 0x20) out.append(String.format("\\u%04x", (int) c));
                    else out.append(c);
                }
            }
        }
        return out.toString();
    }
}