// Copyright 2021 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>

#include <vector>

#include "blobfs-compression.h"
#include "src/lib/chunked-compression/chunked-compressor.h"
#include "src/lib/chunked-compression/status.h"

namespace blobfs_compress {
namespace {
using ::chunked_compression::ChunkedCompressor;
using ::chunked_compression::CompressionParams;
using ::chunked_compression::ToZxStatus;

constexpr const char kAnsiUpLine[] = "\33[A";
constexpr const char kAnsiClearLine[] = "\33[2K\r";
}  // namespace

// ProgressWriter writes live a progress indicator to stdout. Updates are written in-place
// (using ANSI control codes to rewrite the current line).
class ProgressWriter {
 public:
  explicit ProgressWriter(int refresh_hz = 60) : refresh_hz_(refresh_hz) {
    last_report_ = std::chrono::steady_clock::time_point::min();
    printf("\n");
  }

  void Update(const char* fmt, ...) {
    auto now = std::chrono::steady_clock::now();
    if (now < last_report_ + refresh_duration()) {
      return;
    }
    last_report_ = now;
    printf("%s%s", kAnsiUpLine, kAnsiClearLine);
    va_list args;
    va_start(args, fmt);
    vprintf(fmt, args);
    va_end(args);
    fflush(stdout);
  }

  void Final(const char* fmt, ...) {
    printf("%s%s", kAnsiUpLine, kAnsiClearLine);
    va_list args;
    va_start(args, fmt);
    vprintf(fmt, args);
    va_end(args);
    fflush(stdout);
  }

  std::chrono::steady_clock::duration refresh_duration() const {
    return std::chrono::seconds(1) / refresh_hz_;
  }

 private:
  std::chrono::steady_clock::time_point last_report_;
  int refresh_hz_;
};

// Validate command line |options| used for compressing.
zx_status_t ValidateCliOptions(const CompressionCliOptionStruct& options) {
  if (options.source_file.empty()) {
    return ZX_ERR_INVALID_ARGS;
  }

  // Check source file.
  if (!options.source_file_fd.is_valid()) {
    fprintf(stderr, "Failed to open '%s'.\n", options.source_file.c_str());
    return ZX_ERR_BAD_PATH;
  }
  {
    struct stat info;
    if (fstat(options.source_file_fd.get(), &info) < 0) {
      fprintf(stderr, "stat(%s) failed: %s\n", options.source_file.c_str(), strerror(errno));
      return ZX_ERR_BAD_STATE;
    }
    if (!S_ISREG(info.st_mode)) {
      fprintf(stderr, "%s is not a regular file\n", options.source_file.c_str());
      return ZX_ERR_NOT_FILE;
    }
  }

  // Check compressed output file (can be empty).
  if (!options.compressed_file.empty() && !options.compressed_file_fd.is_valid()) {
    fprintf(stderr, "Failed to open '%s': %s\n", options.compressed_file.c_str(), strerror(errno));
    return ZX_ERR_BAD_PATH;
  }

  return ZX_OK;
}

// Returns 0 if the compression runs successfully; otherwise non-zero values.
// This method reads |src_sz| from |src|, compresses it using the compression
// |params|, and then writes the compressed bytes to |dest_write_buf| and the
// compressed size to |out_compressed_size|.
//
// |dest_write_buf| can be nullptr if wanting the final compressed size only.
// However, even if |dest_write_buf| is set to nullptr, there will still be
// temporary RAM consumption for storing compressed data due to current internal
// compression API design.
zx_status_t BlobfsCompress(const uint8_t* src, const size_t src_sz, uint8_t* dest_write_buf,
                           size_t* out_compressed_size, CompressionParams params) {
  ChunkedCompressor compressor(params);

  ProgressWriter progress;
  compressor.SetProgressCallback([&](size_t bytes_read, size_t bytes_total, size_t bytes_written) {
    progress.Update("%2.0f%% (%lu bytes written)\n",
                    static_cast<double>(bytes_read) / static_cast<double>(bytes_total) * 100,
                    bytes_written);
  });

  size_t compressed_size;
  size_t output_limit = params.ComputeOutputSizeLimit(src_sz);
  std::vector<uint8_t> output_buffer;

  // The caller does not need the compressed data. However, the compressor
  // still requires a write buffer to store the compressed output.
  if (dest_write_buf == nullptr) {
    output_buffer.resize(output_limit);
    dest_write_buf = output_buffer.data();
  }

  const auto compression_status =
      compressor.Compress(src, src_sz, dest_write_buf, output_limit, &compressed_size);
  if (compression_status != chunked_compression::kStatusOk) {
    return ToZxStatus(compression_status);
  }

  double saving_ratio = static_cast<double>(src_sz) - static_cast<double>(compressed_size);
  if (src_sz) {
    saving_ratio /= static_cast<double>(src_sz);
  } else {
    saving_ratio = 0;
  }
  progress.Final("Wrote %lu bytes (%.2f%% space saved).\n", compressed_size, saving_ratio * 100);

  *out_compressed_size = compressed_size;
  return ZX_OK;
}
}  // namespace blobfs_compress