//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include "THttpGetThread.h"
#pragma package(smart_init)
#pragma link "wininet.lib"
//---------------------------------------------------------------------------
int GetFileSize(const AnsiString &FileName)
{
    int FileSize=0;
    HANDLE hFile=CreateFile(FileName.c_str(),
                    GENERIC_READ,
                    FILE_SHARE_READ,
                    NULL,
                    OPEN_EXISTING,
                    FILE_ATTRIBUTE_NORMAL,
                    NULL);
    if(hFile!=INVALID_HANDLE_VALUE)
    {
        FileSize=GetFileSize(hFile,NULL);
        CloseHandle(hFile);
    }
    return FileSize;
}
//---------------------------------------------------------------------------

__fastcall THttpGetThread::THttpGetThread(TObject *Owner): TThread(true)
{
    FreeOnTerminate = True;   // 自動刪除
    FRepeatCount=5;

    FIndex=0;
    FOwner=Owner;

    FFromBreakpoint=false;
    FSuccess=false;
    FConnected=false;
    iFileHandle=-1;
    FFileSize=-2;
    dwStart=0;
    dwTotal=0;
}
//---------------------------------------------------------------------------
void __fastcall THttpGetThread::Execute()
{
    for(int i=0;i<FRepeatCount;i++)
    {
        StartHttpGet();
        GetWebFileSize();
        SetFilePointer();
        DoHttpGet();
        EndHttpGet();
        if(FSuccess)break;
    }
    // 調用完成事件
    if(FSuccess)
        DoOnComplete();

    //else  DoOnError();
}
//---------------------------------------------------------------------------
// 從URL中提取主機名稱和下載文件路徑
void THttpGetThread::ParseURL(void)
{
    AnsiString URL=FURL;
    int i=URL.Pos("http://");
    if(i>0)
    {
        URL.Delete(1, 7);
    }
    i=URL.Pos("/");
    FHostName = URL.SubString(1, i-1);
    FDownPath = URL.SubString(i, URL.Length());
}
//---------------------------------------------------------------------------
// 打開Internet句柄，初使化下載環境
void THttpGetThread::StartHttpGet(void)
{
    if(FConnected)return;
    ParseURL();
    try
    {
        // 1.建立會話
        FhSession = InternetOpen("http-get-demo",
                    INTERNET_OPEN_TYPE_PRECONFIG,
                    NULL,NULL,
                    0);         // 同步方式
        if( FhSession==NULL)throw(Exception("Error：InterOpen"));
        DoOnStatusText("ok：InterOpen");
        // 2.建立連接
        FhConnect=InternetConnect(FhSession,
                    FHostName.c_str(),
                    INTERNET_DEFAULT_HTTP_PORT,
                    NULL,NULL,
                    INTERNET_SERVICE_HTTP, 0, 0);
        if(FhConnect==NULL)throw(Exception("Error：InternetConnect"));
        DoOnStatusText("ok：InternetConnect");
        // 3.初使化下載請求
        const char *FAcceptTypes = "*/*";
        FhRequest = HttpOpenRequest(FhConnect,
                    "GET",
                    FDownPath.c_str(),
                    "HTTP/1.0",
                    NULL,
                    &FAcceptTypes,
                    INTERNET_FLAG_RELOAD,
                    0);
        if( FhRequest==NULL)throw(Exception("Error：HttpOpenRequest"));
        DoOnStatusText("ok：HttpOpenRequest");
        // 4.發送下載請求
        HttpSendRequest(FhRequest, NULL, 0, NULL, 0);
        DoOnStatusText("ok：HttpSendRequest");
        FConnected=true;
    }catch(Exception &exception)
    {
        EndHttpGet();
        DoOnStatusText(exception.Message);
    }
}
//---------------------------------------------------------------------------
int __fastcall THttpGetThread::GetWebFileSize(void)
{
    if(FFileSize>-2)return FFileSize;
    FFileSize=-1;
    if(FConnected==false)StartHttpGet();
    if(FConnected==false)return FFileSize;
    try
    {
        // 取得文件的大小
        DWORD BufLen=HTTPGET_BUFFER_MAX;
        DWORD dwIndex=0;
        bool RetQueryInfo=HttpQueryInfo(FhRequest,
                    HTTP_QUERY_CONTENT_LENGTH,
                    Buffer, &BufLen,
                    &dwIndex);
        if( RetQueryInfo==false) throw(Exception("Error：HttpQueryInfo"));
        DoOnStatusText("ok：HttpQueryInfo");
        FFileSize=StrToInt(Buffer); // 文件大小
        DoOnGetFileSize(FFileSize);
    }catch(Exception &exception)
    {
        DoOnStatusText(exception.Message);
    }
    return FFileSize;
}
//---------------------------------------------------------------------------
bool __fastcall THttpGetThread::SetFilePointer(void)
{
    int Size=GetWebFileSize();
    if(Size<0)return false;
    if(dwStart==0)return true;
    try
    {
        // 調整文件指針
        bool ReadReturn=InternetSetFilePointer(FhRequest,
                    dwStart,NULL,FILE_BEGIN,0);
        if( ReadReturn==false) throw(Exception("Error：InternetSetFilePointer"));
        DoOnStatusText("ok：InternetSetFilePointer");
        return true;
    }catch(Exception &exception)
    {
        DoOnStatusText(exception.Message);
    }
    return false;
}
//---------------------------------------------------------------------------
// 打開輸出文件，以保存下載的數據
DWORD THttpGetThread::OpenOutFile(void)
{
    try
    {
        // 打開輸出文件，準備保存下載的數據
        if(FileExists(FOutFileName))
        {
            if(FFromBreakpoint) // 使用斷點續傳
            {
                DWORD dwCount=GetFileSize(FOutFileName);
                if(dwCount>0)
                {
                    iFileHandle=FileOpen(FOutFileName,fmOpenWrite);
                    FileSeek(iFileHandle,0,2);   // 移動文件指針到末尾
                    if(iFileHandle==-1) throw(Exception("Error：FileCreate"));
                    DoOnStatusText("ok:OpenFile");
                    return dwCount;
                }
            }
            DeleteFile(FOutFileName);
        }
        iFileHandle=FileCreate(FOutFileName);
        if(iFileHandle==-1) throw(Exception("Error：FileCreate"));
        DoOnStatusText("ok:CreateFile");
    }catch(Exception &exception)
    {
        DoOnStatusText(exception.Message);
    }
    return 0;
}
//---------------------------------------------------------------------------
// 執行下載過程
void THttpGetThread::DoHttpGet(void)
{
    if(FConnected==false)return;
    DWORD dwCount=OpenOutFile();
    if(dwCount>0)   // 調整文件指針
    {
        dwStart = dwStart + dwCount;
        if(!SetFilePointer())   // 服務器不支持操作
        {
            // 清除輸出文件
            FileSeek(iFileHandle,0,0);   // 移動文件指針到頭部
        }
    }
    try
    {
        // 發出下載事件
        DoOnStatusText("StartGet：InternetReadFile");
        // 讀取數據
        DWORD dwRequest;    // 請求下載的字節數
        DWORD dwRead;       // 實際讀出的字節數
        dwRequest=HTTPGET_BUFFER_MAX;
        while(true)
        {
            Application->ProcessMessages();
            // 修正需要下載的字節數，使得dwRequest + dwCount<dwTotal
            if(dwTotal>0)     // dwTotal<=0表示下載到文件結束
            {
                if(dwRequest+dwCount>dwTotal)
                    dwRequest=dwTotal-dwCount;
            }
            bool ReadReturn = InternetReadFile(FhRequest,
                    (LPVOID)Buffer,
                    dwRequest,
                    &dwRead);
            if(!ReadReturn)break;
            if(dwRead==0)break;
            // 保存數據
            Buffer[dwRead]='\0';
            FileWrite(iFileHandle, Buffer, dwRead);
            dwCount = dwCount + dwRead;
            // 發出下載進程事件
            DoOnProgress(dwCount);
            if(dwTotal>0)     // Count<=0表示下載到文件結束
            {
                if(dwCount>=dwTotal)break;
            }
        }
    }catch(Exception &exception)
    {
        DoOnStatusText(exception.Message);
    }
    FileClose(iFileHandle);

    DoOnStatusText("End：InternetReadFile");
    if(dwCount==dwTotal)FSuccess=true;
}
//---------------------------------------------------------------------------
// 關閉Internet句柄
void THttpGetThread::EndHttpGet(void)
{
    if(FConnected)
    {
        DoOnStatusText("Closing:InternetConnect");
        try
        {
            InternetCloseHandle(FhRequest);
            InternetCloseHandle(FhConnect);
            InternetCloseHandle(FhSession);
        }catch(...){}
        FhSession=NULL;
        FhConnect=NULL;
        FhRequest=NULL;
        FConnected=false;
        DoOnStatusText("Closed:InternetConnect");
    }
}
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
void THttpGetThread::DoOnGetFileSize(int Size)
{
    if(FOnGetFileSize)
        FOnGetFileSize(FOwner,Size);
}
//---------------------------------------------------------------------------
void THttpGetThread::DoOnProgress(int Position)
{
    if(FOnProgress)
        FOnProgress(FOwner,Position,dwTotal,FIndex);
}
//---------------------------------------------------------------------------
void THttpGetThread::DoOnStatusText(AnsiString Text)
{
    if(FOnStatusText)
        FOnStatusText(FOwner,Text,FIndex);
}
//---------------------------------------------------------------------------
void THttpGetThread::DoOnComplete(void)
{
    if(FOnComplete)
        FOnComplete(FOwner,FIndex);
}
//---------------------------------------------------------------------------
void THttpGetThread::DoOnError(int errorcode)
{
    if(FOnError)
        FOnError(FOwner,errorcode);
}
//---------------------------------------------------------------------------