package com.razz.dfashion.security;

import com.code_intelligence.jazzer.junit.FuzzTest;
import com.google.gson.JsonParseException;
import com.razz.dfashion.bbmodel.BbModelParser;

import org.junit.jupiter.api.Test;

import java.io.StringReader;

import static org.junit.jupiter.api.Assertions.*;

/**
 * Security corpus + fuzz harness for {@link BbModelParser}. The parser runs only on the
 * author's local disk, but still handles untrusted JSON (the author could have downloaded
 * a malicious .bbmodel), so every rejection rule matters.
 *
 * <p>Fuzz inputs are fed as UTF-8 byte arrays. Legitimate rejections are any subtype of
 * {@link JsonParseException} (including {@code BadBbmodelException}). A {@link StackOverflowError},
 * {@link NullPointerException}, or any non-JsonParseException is a bug Jazzer should surface.
 */
class BbModelParserSecurityTest {

    @Test
    void acceptsMinimalValidModel() {
        String json = "{" +
                "\"meta\":{\"format_version\":\"5.0\"}," +
                "\"resolution\":{\"width\":64,\"height\":64}," +
                "\"elements\":[]," +
                "\"groups\":[]," +
                "\"outliner\":[]" +
                "}";
        assertDoesNotThrow(() -> BbModelParser.parse(new StringReader(json)));
    }

    @Test
    void rejectsOldFormatVersion() {
        String json = "{" +
                "\"meta\":{\"format_version\":\"4.5\"}," +
                "\"resolution\":{\"width\":64,\"height\":64}," +
                "\"elements\":[],\"groups\":[],\"outliner\":[]" +
                "}";
        assertThrows(JsonParseException.class, () -> BbModelParser.parse(new StringReader(json)));
    }

    @Test
    void rejectsResolutionOverCap() {
        String json = "{" +
                "\"meta\":{\"format_version\":\"5.0\"}," +
                "\"resolution\":{\"width\":" + (BbModelParser.MAX_RESOLUTION + 1) + ",\"height\":64}," +
                "\"elements\":[],\"groups\":[],\"outliner\":[]" +
                "}";
        assertThrows(JsonParseException.class, () -> BbModelParser.parse(new StringReader(json)));
    }

    @Test
    void rejectsNanFloat() {
        String json = "{" +
                "\"meta\":{\"format_version\":\"5.0\"}," +
                "\"resolution\":{\"width\":64,\"height\":64}," +
                "\"elements\":[{\"type\":\"cube\",\"uuid\":\"a\",\"name\":\"n\"," +
                "\"from\":[\"NaN\",0,0],\"to\":[1,1,1],\"origin\":[0,0,0],\"rotation\":[0,0,0]," +
                "\"inflate\":0,\"faces\":{}}]," +
                "\"groups\":[],\"outliner\":[\"a\"]" +
                "}";
        // GSON parses NaN-as-string into Float.NaN (depending on lenient mode); post-parse
        // validation rejects non-finite floats. Either way, a JsonParseException is expected.
        assertThrows(JsonParseException.class, () -> BbModelParser.parse(new StringReader(json)));
    }

    @Test
    void rejectsInfinityFloat() {
        String json = "{" +
                "\"meta\":{\"format_version\":\"5.0\"}," +
                "\"resolution\":{\"width\":64,\"height\":64}," +
                "\"elements\":[{\"type\":\"cube\",\"uuid\":\"a\",\"name\":\"n\"," +
                "\"from\":[0,0,0],\"to\":[1,1,1],\"origin\":[0,0,0]," +
                "\"rotation\":[\"Infinity\",0,0]," +
                "\"inflate\":0,\"faces\":{}}]," +
                "\"groups\":[],\"outliner\":[\"a\"]" +
                "}";
        assertThrows(JsonParseException.class, () -> BbModelParser.parse(new StringReader(json)));
    }

    @Test
    void rejectsCoordOutOfRange() {
        String json = "{" +
                "\"meta\":{\"format_version\":\"5.0\"}," +
                "\"resolution\":{\"width\":64,\"height\":64}," +
                "\"elements\":[{\"type\":\"cube\",\"uuid\":\"a\",\"name\":\"n\"," +
                "\"from\":[1e9,0,0],\"to\":[1,1,1],\"origin\":[0,0,0],\"rotation\":[0,0,0]," +
                "\"inflate\":0,\"faces\":{}}]," +
                "\"groups\":[],\"outliner\":[\"a\"]" +
                "}";
        assertThrows(JsonParseException.class, () -> BbModelParser.parse(new StringReader(json)));
    }

    @Test
    void rejectsDuplicateElementUuid() {
        String json = "{" +
                "\"meta\":{\"format_version\":\"5.0\"}," +
                "\"resolution\":{\"width\":64,\"height\":64}," +
                "\"elements\":[" +
                "  {\"type\":\"cube\",\"uuid\":\"dup\",\"name\":\"n\"," +
                "   \"from\":[0,0,0],\"to\":[1,1,1],\"origin\":[0,0,0],\"rotation\":[0,0,0],\"inflate\":0,\"faces\":{}}," +
                "  {\"type\":\"cube\",\"uuid\":\"dup\",\"name\":\"n\"," +
                "   \"from\":[0,0,0],\"to\":[1,1,1],\"origin\":[0,0,0],\"rotation\":[0,0,0],\"inflate\":0,\"faces\":{}}" +
                "]," +
                "\"groups\":[],\"outliner\":[\"dup\"]" +
                "}";
        assertThrows(JsonParseException.class, () -> BbModelParser.parse(new StringReader(json)));
    }

    @Test
    void rejectsOutlinerRefToUnknownElement() {
        String json = "{" +
                "\"meta\":{\"format_version\":\"5.0\"}," +
                "\"resolution\":{\"width\":64,\"height\":64}," +
                "\"elements\":[]," +
                "\"groups\":[]," +
                "\"outliner\":[\"ghost-uuid\"]" +
                "}";
        assertThrows(JsonParseException.class, () -> BbModelParser.parse(new StringReader(json)));
    }

    @Test
    void rejectsOutlinerOverDepthCap() {
        // Build a chain of groups deeper than MAX_OUTLINER_DEPTH. Each group is a GroupRef
        // whose single child is the next GroupRef.
        int depth = BbModelParser.MAX_OUTLINER_DEPTH + 5;
        StringBuilder groups = new StringBuilder();
        StringBuilder outliner = new StringBuilder();
        for (int i = 0; i < depth; i++) {
            if (i > 0) groups.append(',');
            groups.append("{\"uuid\":\"g").append(i).append("\",\"name\":\"g\"," +
                    "\"origin\":[0,0,0],\"rotation\":[0,0,0]}");
        }
        // Outliner is a nested object tree referencing g0 → g1 → ... → g(depth-1).
        for (int i = 0; i < depth; i++) {
            outliner.append("{\"uuid\":\"g").append(i).append("\",\"children\":[");
        }
        for (int i = 0; i < depth; i++) outliner.append("]}");

        String json = "{" +
                "\"meta\":{\"format_version\":\"5.0\"}," +
                "\"resolution\":{\"width\":64,\"height\":64}," +
                "\"elements\":[]," +
                "\"groups\":[" + groups + "]," +
                "\"outliner\":[" + outliner + "]" +
                "}";
        assertThrows(JsonParseException.class, () -> BbModelParser.parse(new StringReader(json)));
    }

    @Test
    void rejectsMalformedJson() {
        assertThrows(JsonParseException.class, () -> BbModelParser.parse(new StringReader("{ not json")));
    }

    @Test
    void rejectsEmpty() {
        assertThrows(Exception.class, () -> BbModelParser.parse(new StringReader("")));
    }

    // ---- fuzz harness ----

    /**
     * Fuzz the JSON parser with random UTF-8. Legit rejection = anything JsonParseException-ish.
     * Other exceptions point at missing defense in the parser.
     */
    @FuzzTest(maxDuration = "30s")
    void fuzzParse(byte[] input) {
        try {
            BbModelParser.parse(new StringReader(new String(input, java.nio.charset.StandardCharsets.UTF_8)));
        } catch (JsonParseException | IllegalStateException | NumberFormatException expected) {
            // All legitimate rejection paths from GSON + validator.
        }
    }
}