// SPDX-FileCopyrightText: 2023 Unity Technologies and the glTFast authors
// SPDX-License-Identifier: Apache-2.0

using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using UnityEngine;
using UnityEngine.Assertions;

namespace GLTFast.Schema
{

    class JsonWriter
    {

        StreamWriter m_Stream;

        bool m_Separation;

        public JsonWriter(StreamWriter stream)
        {
            m_Stream = stream;
            OpenBrackets();
        }

        public void OpenBrackets()
        {
            m_Stream.Write('{');
            m_Separation = false;
        }

        public void AddProperty(string name)
        {
            CertifyValidJsonString(name);
            Separate();
            m_Stream.Write('"');
            m_Stream.Write(name);
            m_Stream.Write("\":");
            m_Separation = false;
        }

        public void AddObject()
        {
            Separate();
            m_Stream.Write('{');
            m_Separation = false;
        }

        public void AddArray(string name)
        {
            CertifyValidJsonString(name);
            Separate();
            m_Stream.Write('"');
            m_Stream.Write(name);
            m_Stream.Write("\":[");
            m_Separation = false;
        }

        public void CloseArray()
        {
            m_Stream.Write(']');
            m_Separation = true;
        }

        public void AddArrayProperty<T>(string name, IEnumerable<T> values)
        {
            AddArray(name);
            foreach (var value in values)
            {
                Separate();
                m_Stream.Write(value.ToString());
            }
            CloseArray();
        }

        public void AddArrayProperty(string name, IEnumerable<float> values)
        {
            AddArray(name);
            foreach (var value in values)
            {
                Separate();
                m_Stream.Write(value.ToString("R", CultureInfo.InvariantCulture));
            }
            CloseArray();
        }

        public void AddArrayProperty(string name, IEnumerable<string> values)
        {
            AddArray(name);
            foreach (var value in values)
            {
                CertifyValidJsonString(value);
                Separate();
                m_Stream.Write('"');
                m_Stream.Write(value);
                m_Stream.Write('"');
            }
            CloseArray();
        }

        public void AddArrayPropertySafe(string name, IEnumerable<string> values)
        {
            AddArray(name);
            foreach (var value in values)
            {
                Separate();
                m_Stream.Write('"');
                WriteStringValueSafe(value);
                m_Stream.Write('"');
            }
            CloseArray();
        }

        public void AddProperty<T>(string name, T value)
        {
            CertifyValidJsonString(name);
            Separate();
            m_Stream.Write('"');
            m_Stream.Write(name);
            m_Stream.Write("\":");
            m_Stream.Write(value.ToString());
        }

        public void AddProperty(string name, float value)
        {
            CertifyValidJsonString(name);
            Separate();
            m_Stream.Write('"');
            m_Stream.Write(name);
            m_Stream.Write("\":");
            m_Stream.Write(value.ToString("R", CultureInfo.InvariantCulture));
        }

        public void AddProperty(string name, string value)
        {
            CertifyValidJsonString(name);
            CertifyValidJsonString(value);
            Separate();
            m_Stream.Write('"');
            m_Stream.Write(name);
            m_Stream.Write("\":\"");
            m_Stream.Write(value);
            m_Stream.Write('"');
        }

        public void AddPropertySafe(string name, string value)
        {
            CertifyValidJsonString(name);
            Separate();
            m_Stream.Write('"');
            m_Stream.Write(name);
            m_Stream.Write("\":\"");
            WriteStringValueSafe(value);
            m_Stream.Write('"');
        }

        public void AddProperty(string name, bool value)
        {
            CertifyValidJsonString(name);
            Separate();
            m_Stream.Write('"');
            m_Stream.Write(name);
            m_Stream.Write("\":");
            m_Stream.Write(value ? "true" : "false");
        }

        void Separate()
        {
            if (m_Separation)
            {
                m_Stream.Write(',');
            }
            m_Separation = true;
        }

        public void Close()
        {
            m_Stream.Write('}');
            m_Separation = true;
        }

        void WriteStringValueSafe(string value)
        {
            foreach (var c in value)
            {
                switch (c)
                {
                    case '\\':
                        m_Stream.Write(@"\\");
                        break;
                    case '\f':
                        m_Stream.Write("\\f");
                        break;
                    case '\n':
                        m_Stream.Write("\\n");
                        break;
                    case '\r':
                        m_Stream.Write("\\r");
                        break;
                    case '\t':
                        m_Stream.Write("\\t");
                        break;
                    case '"':
                        m_Stream.Write("\\\"");
                        break;
                    default:
                        m_Stream.Write(c);
                        break;
                }
            }
        }

        [Conditional("DEBUG")]
        static void CertifyValidJsonString(string value)
        {
#if DEBUG
            var invalidChars = new[]
            {
                '\\',
                '\f',
                '\n',
                '\r',
                '\t',
                '"'
            };

            Assert.IsTrue(value.IndexOfAny(invalidChars) < 0, "JSON string literal contains invalid characters");
#endif
        }
    }
}