text: /*
    Licensed to the Apache Software Foundation (ASF) under one
    or more contributor license agreements.  See the NOTICE file
    distributed with this work for additional information
    regarding copyright ownership.  The ASF licenses this file
    to you under the Apache License, Version 2.0 (the
    "License"); you may not use this file except in compliance
    with the License.  You may obtain a copy of the License at
  
    http://www.apache.org/licenses/LICENSE-2.0
  
    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
  */
  
  
  #include "ts_lua_util.h"
  
  
  static int ts_lua_transform_handler(TSCont contp, ts_lua_http_transform_ctx *transform_ctx, TSEvent event, int n);
  
  
  int
  ts_lua_transform_entry(TSCont contp, TSEvent ev, void *edata)
  {
    int n, event;
    TSVIO input_vio;
    ts_lua_http_transform_ctx *transform_ctx;
  
    event = (int)ev;
    transform_ctx = (ts_lua_http_transform_ctx *)TSContDataGet(contp);
  
    if (TSVConnClosedGet(contp)) {
      ts_lua_destroy_http_transform_ctx(transform_ctx);
      return 0;
    }
  
    n = 0;
  
    switch (event) {
    case TS_EVENT_ERROR:
      input_vio = TSVConnWriteVIOGet(contp);
      TSContCall(TSVIOContGet(input_vio), TS_EVENT_ERROR, input_vio);
      break;
  
    case TS_EVENT_VCONN_WRITE_COMPLETE:
      TSVConnShutdown(TSTransformOutputVConnGet(contp), 0, 1);
      break;
  
    case TS_LUA_EVENT_COROUTINE_CONT:
      n = (intptr_t)edata;
    /* FALL THROUGH */
    case TS_EVENT_VCONN_WRITE_READY:
    default:
      ts_lua_transform_handler(contp, transform_ctx, event, n);
      break;
    }
  
    return 0;
  }
  
  static int
  ts_lua_transform_handler(TSCont contp, ts_lua_http_transform_ctx *transform_ctx, TSEvent event, int n)
  {
    TSVConn output_conn;
    TSVIO input_vio;
    TSIOBufferReader input_reader;
    TSIOBufferBlock blk;
    int64_t toread, towrite, blk_len, upstream_done, input_avail, l;
    const char *start;
    const char *res;
    size_t res_len;
    int ret, eos, write_down, rc, top;
    ts_lua_coroutine *crt;
    ts_lua_cont_info *ci;
  
    lua_State *L;
    TSMutex mtxp;
  
    ci = &transform_ctx->cinfo;
    crt = &ci->routine;
  
    mtxp = crt->mctx->mutexp;
    L = crt->lua;
  
    output_conn = TSTransformOutputVConnGet(contp);
    input_vio = TSVConnWriteVIOGet(contp);
  
    if (!TSVIOBufferGet(input_vio)) {
      if (transform_ctx->output.vio) {
        TSVIONBytesSet(transform_ctx->output.vio, transform_ctx->total);
        TSVIOReenable(transform_ctx->output.vio);
      }
      return 0;
    }
  
    input_reader = TSVIOReaderGet(input_vio);
  
    if (!transform_ctx->output.buffer) {
      transform_ctx->output.buffer = TSIOBufferCreate();
      transform_ctx->output.reader = TSIOBufferReaderAlloc(transform_ctx->output.buffer);
  
      transform_ctx->reserved.buffer = TSIOBufferCreate();
      transform_ctx->reserved.reader = TSIOBufferReaderAlloc(transform_ctx->reserved.buffer);
  
      transform_ctx->upstream_bytes = TSVIONBytesGet(input_vio);
      transform_ctx->downstream_bytes = INT64_MAX;
    }
  
    input_avail = TSIOBufferReaderAvail(input_reader);
    upstream_done = TSVIONDoneGet(input_vio);
    toread = TSVIONTodoGet(input_vio);
  
    if (toread <= input_avail) { // upstream finished
      eos = 1;
    } else {
      eos = 0;
    }
  
    if (input_avail > 0) {
      // move to the reserved.buffer
      TSIOBufferCopy(transform_ctx->reserved.buffer, input_reader, input_avail, 0);
  
      // reset input
      TSIOBufferReaderConsume(input_reader, input_avail);
      TSVIONDoneSet(input_vio, upstream_done + input_avail);
    }
  
    write_down = 0;
    towrite = TSIOBufferReaderAvail(transform_ctx->reserved.reader);
  
    TSMutexLock(mtxp);
    ts_lua_set_cont_info(L, ci);
  
    do {
      if (event == TS_LUA_EVENT_COROUTINE_CONT) {
        event = 0;
        goto launch;
      } else {
        n = 2;
      }
  
      if (towrite == 0)
        break;
  
      blk = TSIOBufferReaderStart(transform_ctx->reserved.reader);
      start = TSIOBufferBlockReadStart(blk, transform_ctx->reserved.reader, &blk_len);
  
      lua_pushlightuserdata(L, transform_ctx);
      lua_rawget(L, LUA_GLOBALSINDEX); /* push function */
  
      if (towrite > blk_len) {
        lua_pushlstring(L, start, (size_t)blk_len);
        towrite -= blk_len;
        TSIOBufferReaderConsume(transform_ctx->reserved.reader, blk_len);
      } else {
        lua_pushlstring(L, start, (size_t)towrite);
        TSIOBufferReaderConsume(transform_ctx->reserved.reader, towrite);
        towrite = 0;
      }
  
      if (!towrite && eos) {
        lua_pushinteger(L, 1); /* second param, data finished */
      } else {
        lua_pushinteger(L, 0); /* second param, data not finish */
      }
  
    launch:
      rc = lua_resume(L, n);
      top = lua_gettop(L);
  
      switch (rc) {
      case LUA_YIELD: // coroutine yield
        TSMutexUnlock(mtxp);
        return 0;
  
      case 0: // coroutine success
        if (top == 2) {
          ret = lua_tointeger(L, -1); /* 0 is not finished, 1 is finished */
          res = lua_tolstring(L, -2, &res_len);
        } else { // what hells code are you writing ?
          ret = 0;
          res = NULL;
          res_len = 0;
        }
        break;
  
      default: // coroutine failed
        TSError("lua_resume failed: %s", lua_tostring(L, -1));
        ret = 1;
        res = NULL;
        res_len = 0;
        break;
      }
  
      if (res && res_len > 0) {
        if (!transform_ctx->output.vio) {
          l = transform_ctx->downstream_bytes;
          if (ret) {
            l = res_len;
          }
  
          transform_ctx->output.vio = TSVConnWrite(output_conn, contp, transform_ctx->output.reader, l); // HttpSM go on
        }
  
        TSIOBufferWrite(transform_ctx->output.buffer, res, res_len);
        transform_ctx->total += res_len;
        write_down = 1;
      }
  
      lua_pop(L, top);
  
      if (ret || (eos && !towrite)) { // EOS
        eos = 1;
        break;
      }
  
    } while (towrite > 0);
  
    TSMutexUnlock(mtxp);
  
    if (eos && !transform_ctx->output.vio)
      transform_ctx->output.vio = TSVConnWrite(output_conn, contp, transform_ctx->output.reader, 0);
  
    if (write_down || eos)
      TSVIOReenable(transform_ctx->output.vio);
  
    if (toread > input_avail) { // upstream not finished.
      if (eos) {
        TSVIONBytesSet(transform_ctx->output.vio, transform_ctx->total);
        TSContCall(TSVIOContGet(input_vio), TS_EVENT_VCONN_EOS, input_vio);
      } else {
        TSContCall(TSVIOContGet(input_vio), TS_EVENT_VCONN_WRITE_READY, input_vio);
      }
    } else { // upstream is finished.
      TSVIONBytesSet(transform_ctx->output.vio, transform_ctx->total);
      TSContCall(TSVIOContGet(input_vio), TS_EVENT_VCONN_WRITE_COMPLETE, input_vio);
    }
  
    return 0;
  }
  