#region Copyright notice and license
// Copyright 2015, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#endregion

using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Runtime.InteropServices;
using System.Text;

namespace Grpc.Core
{
    /// <summary>
    /// gRPC call metadata.
    /// </summary>
    public class Metadata
    {
        public static readonly Metadata Empty = new Metadata(ImmutableList<MetadataEntry>.Empty);

        readonly ImmutableList<MetadataEntry> entries;

        public Metadata(ImmutableList<MetadataEntry> entries)
        {
            this.entries = entries;
        }

        public ImmutableList<MetadataEntry> Entries
        {
            get
            {
                return this.entries;
            }
        }

        public static Builder CreateBuilder()
        {
            return new Builder();
        }
       
        public struct MetadataEntry
        {
            readonly string key;
            readonly byte[] valueBytes;

            public MetadataEntry(string key, byte[] valueBytes)
            {
                this.key = key;
                this.valueBytes = valueBytes;
            }

            public MetadataEntry(string key, string value)
            {
                this.key = key;
                this.valueBytes = Encoding.ASCII.GetBytes(value);
            }

            public string Key
            {
                get
                {
                    return this.key;
                }
            }

            // TODO: using ByteString would guarantee immutability.
            public byte[] ValueBytes
            {
                get
                {
                    return this.valueBytes;
                }
            }
        }

        public class Builder
        {
            readonly List<Metadata.MetadataEntry> entries = new List<Metadata.MetadataEntry>();

            public List<MetadataEntry> Entries
            {
                get
                {
                    return entries;
                }
            }

            public Builder Add(MetadataEntry entry)
            {
                entries.Add(entry);
                return this;
            }

            public Metadata Build()
            {
                return new Metadata(entries.ToImmutableList());
            }
        }
    }
}