using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Globalization;
using System.Configuration;

namespace Windows.Azure.Storage.Blobs
{
    public enum BlobConnectionModes
    {
        Local,
        Cloud 
    }

    public class ConnectionDetails
    {
        public string Account { get; set; }
        public string Key { get; set; }
        public string Endpoint { get; set; }
        public BlobConnectionModes ConnectionMode {get; set;}

        public ConnectionDetails(BlobConnectionModes connectionMode)
        {
            ConnectionMode = connectionMode;
        }

        public string GetConnectionURI()
        {
            return String.Format(Endpoint, Account);
        }
    }

    /// <summary>
    /// Blob Request is based on the HttpWebRequest. It provides extra capabilities to handle the REST API for Blob Storage
    /// </summary>
    public class BlobRequest 
    {
        private ConnectionDetails connectionDetails;

        public BlobRequest(ConnectionDetails connectionDetails)
        {
            this.connectionDetails = connectionDetails;
        }

        public BlobResponse SetContainerPermissions(string containerName, bool makePublic)
        {
            HttpWebRequest request;

            request = (HttpWebRequest)WebRequest.Create(GetUri(containerName, new string [] {"acl"}));

            request.Method = "PUT";
            request.ContentLength = 0;

            SetDateHeader(request);

            SetContainerACL(request, makePublic);

            SetAuthorizationHeader(request);

            return DispatchRequest(request);
        }
        
        public BlobResponse CreateContainer(string containerName)
        {
            HttpWebRequest request;

            request = (HttpWebRequest)WebRequest.Create(GetUri(containerName, null));

            request.Method = "PUT";
            request.ContentLength = 0;

            SetDateHeader(request);

            SetAuthorizationHeader(request);

            return DispatchRequest(request);
            
        }

        public BlobResponse RemoveContainer(string containerName)
        {
            HttpWebRequest request;

            request = (HttpWebRequest)WebRequest.Create(GetUri(containerName, null));

            request.Method = "DELETE";
            request.ContentLength = 0;

            SetDateHeader(request);

            SetAuthorizationHeader(request);

            return DispatchRequest(request);

        }

        public BlobResponse GetContainers()
        {
            HttpWebRequest request;

            request = (HttpWebRequest)WebRequest.Create(GetUri(String.Empty, new string [] {"list"}));

            request.Method = "GET";
            request.ContentLength = 0;

            SetDateHeader(request);

            SetAuthorizationHeader(request);

            return DispatchRequest(request);

        }

        public BlobResponse UploadBlob(string containerName, string blobName, byte[] blobContents)
        {
            HttpWebRequest request;

            request = (HttpWebRequest)WebRequest.Create(GetUri(String.Format("{0}/{1}", containerName, blobName), null));

            request.Method = "PUT";
            request.ContentLength = blobContents.Length;

            SetDateHeader(request);

            SetAuthorizationHeader(request);

            SetBodyContent(request,blobContents);

            return DispatchRequest(request);

        }

        public BlobResponse SetBlobMetadata(string containerName, string blobName, Dictionary<String,String> metadata)
        {
            HttpWebRequest request;

            request = (HttpWebRequest)WebRequest.Create(GetUri(String.Format("{0}/{1}", containerName, blobName), new string [] {"metadata"}));

            request.Method = "PUT";
            request.ContentLength = 0;

            SetDateHeader(request);

            SetMetadataHeaders(request, metadata);

            SetAuthorizationHeader(request);

            return DispatchRequest(request);

        }

        public BlobResponse GetBlobMetadata(string containerName, string blobName)
        {
            HttpWebRequest request;

            request = (HttpWebRequest)WebRequest.Create(GetUri(String.Format("{0}/{1}", containerName, blobName), new string[] { "metadata" }));

            request.Method = "HEAD";
            request.ContentLength = 0;

            SetDateHeader(request);

            SetAuthorizationHeader(request);

            return DispatchRequest(request);

        }

        private void SetMetadataHeaders(HttpWebRequest request, Dictionary<string, string> metadata)
        {
            foreach (KeyValuePair<string,string> metadataItem in metadata)
            {
                request.Headers.Add(String.Format("x-ms-meta-{0}:{1}", metadataItem.Key, metadataItem.Value));
            }
        }

        public BlobResponse GetBlobs(string containerName)
        {
            HttpWebRequest request;

            request = (HttpWebRequest)WebRequest.Create(GetUri(String.Format("{0}", containerName), new string [] {"list"}));

            request.Method = "GET";
            request.ContentLength = 0;

            SetDateHeader(request);

            SetAuthorizationHeader(request);

            return DispatchRequest(request);
        }

        private void SetContainerACL(HttpWebRequest request, bool makePublic)
        {
            request.Headers.Add("x-ms-prop-publicaccess", makePublic.ToString().ToLower());
        }

        private void SetBodyContent(HttpWebRequest request, byte[] blobContents)
        {
            request.GetRequestStream().Write(blobContents, 0, blobContents.Length);
        }
        

        private string GetUri(string function, string [] comps)
        {
            StringBuilder uri = new StringBuilder();

            uri.Append(this.connectionDetails.GetConnectionURI());
            uri.AppendFormat("{0}", function);

            if (comps != null && comps.Length > 0)
            {
                uri.Append("?");
                for(int i = 0; i < comps.Length; i++)
                {
                    uri.AppendFormat("comp={0}", comps[i]);
                    if (i < comps.Length - 1)
                    {
                        uri.Append("&");
                    }
                }
            }

            return uri.ToString();
        }

        private BlobResponse DispatchRequest(HttpWebRequest request)
        {
            try
            {
                using(HttpWebResponse response = (HttpWebResponse)request.GetResponse())
                {
                    return new BlobResponse(response);
                }
            }
            catch (WebException ex)
            {
                using (HttpWebResponse errorResponse = (HttpWebResponse)ex.Response)
                {
                    return new BlobResponse(errorResponse);
                }
            }
        }

        private void SetAuthorizationHeader(HttpWebRequest request)
        {
            // Now sign the request
            // For a blob, you need to use this Canonical form:
            //  VERB + "\n" +
            //  Content - MD5 + "\n" +
            //  Content - Type + "\n" +
            //  Date + "\n" +
            //  CanonicalizedHeaders +
            //  CanonicalizedResource;

            StringBuilder signature = new StringBuilder();

            // Verb
            signature.Append(String.Format("{0}{1}", request.Method,"\n"));

            // Content-MD5 Header
            signature.Append("\n");

            // Content-Type Header
            signature.Append("\n");

            // Then Date, if we have already added the x-ms-date header, leave this null
            signature.Append("\n");

            // Now for CanonicalizedHeaders
            // TODO: Replace with LINQ statement
            foreach (string header in request.Headers)
            {
                if (header.StartsWith("x-ms"))
                {
                    signature.Append(String.Format("{0}:{1}\n", header, request.Headers[header]));
                }
            }

            // Now for CanonicalizedResource
            // Format is /{0}/{1} where 0 is name of the account and 1 is resources URI path
            signature.Append(String.Format("/{0}{1}", connectionDetails.Account, request.RequestUri.PathAndQuery));

            // Next, we need to encode our signature using the HMAC-SHA256 algorithm
            byte[] signatureByteForm = System.Text.Encoding.UTF8.GetBytes(signature.ToString());

            System.Security.Cryptography.HMACSHA256 hasher = new System.Security.Cryptography.HMACSHA256(Convert.FromBase64String(connectionDetails.Key));

            // Now build the Authorization header
            String authHeader = String.Format(CultureInfo.InvariantCulture,
                                       "{0} {1}:{2}",
                                       "SharedKey",
                                       connectionDetails.Account,
                                       System.Convert.ToBase64String(hasher.ComputeHash(signatureByteForm)
                                       ));

            // And add the Authorization header to the request
            request.Headers.Add("Authorization", authHeader);
        }

        private void SetDateHeader(HttpWebRequest request)
        {
            request.Headers.Add("x-ms-date", DateTime.UtcNow.ToString("R", CultureInfo.InvariantCulture));
        }
    }
}