/********************************************************************
 * This file includes functions to build fabric dependent bitstream
 *******************************************************************/
#include <string>
#include <algorithm>

/* Headers from vtrutil library */
#include "vtr_assert.h"
#include "vtr_log.h"
#include "vtr_time.h"

/* Headers from openfpgautil library */
#include "openfpga_decode.h"

#include "openfpga_reserved_words.h"
#include "openfpga_naming.h"

#include "bitstream_manager_utils.h"
#include "build_fabric_bitstream.h"

/* begin namespace openfpga */
namespace openfpga {

/********************************************************************
 * This function aims to build a bitstream for configuration chain-like protocol
 * It will walk through all the configurable children under a module
 * in a recursive way, following a Depth-First Search (DFS) strategy
 * For each configuration child, we use its instance name as a key to spot the 
 * configuration bits in bitstream manager.
 * Note that it is guarentee that the instance name in module manager is 
 * consistent with the block names in bitstream manager
 * We use this link to reorganize the bitstream in the sequence of memories as we stored
 * in the configurable_children() and configurable_child_instances() of each module of module manager 
 *******************************************************************/
static 
void rec_build_module_fabric_dependent_chain_bitstream(const BitstreamManager& bitstream_manager,
                                                       const ConfigBlockId& parent_block,
                                                       const ModuleManager& module_manager,
                                                       const ModuleId& parent_module,
                                                       FabricBitstream& fabric_bitstream) {

  /* Depth-first search: if we have any children in the parent_block, 
   * we dive to the next level first! 
   */
  if (0 < bitstream_manager.block_children(parent_block).size()) {
    for (size_t child_id = 0; child_id < module_manager.configurable_children(parent_module).size(); ++child_id) {
      ModuleId child_module = module_manager.configurable_children(parent_module)[child_id]; 
      size_t child_instance = module_manager.configurable_child_instances(parent_module)[child_id]; 
      /* Get the instance name and ensure it is not empty */
      std::string instance_name = module_manager.instance_name(parent_module, child_module, child_instance);
       
      /* Find the child block that matches the instance name! */ 
      ConfigBlockId child_block = bitstream_manager.find_child_block(parent_block, instance_name); 
      /* We must have one valid block id! */
      if (true != bitstream_manager.valid_block_id(child_block))
      VTR_ASSERT(true == bitstream_manager.valid_block_id(child_block));

      /* Go recursively */
      rec_build_module_fabric_dependent_chain_bitstream(bitstream_manager, child_block,
                                                        module_manager, child_module,
                                                        fabric_bitstream);
    }
    /* Ensure that there should be no configuration bits in the parent block */
    VTR_ASSERT(0 == bitstream_manager.block_bits(parent_block).size());
  }

  /* Note that, reach here, it means that this is a leaf node. 
   * We add the configuration bits to the fabric_bitstream,
   * And then, we can return
   */
  for (const ConfigBitId& config_bit : bitstream_manager.block_bits(parent_block)) {
    fabric_bitstream.add_bit(config_bit);
  }
}

/********************************************************************
 * This function aims to build a bitstream for frame-based configuration protocol
 * It will walk through all the configurable children under a module
 * in a recursive way, following a Depth-First Search (DFS) strategy
 * For each configuration child, we use its instance name as a key to spot the 
 * configuration bits in bitstream manager.
 * Note that it is guarentee that the instance name in module manager is 
 * consistent with the block names in bitstream manager
 * We use this link to reorganize the bitstream in the sequence of memories as we stored
 * in the configurable_children() and configurable_child_instances() of each module of module manager 
 *
 * For each configuration bits, we will infer its address based on 
 *  - the child index in the configurable children list of current module
 *  - the child index of all the parent modules in their configurable children list 
 *    until the top in the hierarchy
 *
 * The address will be organized as follows:
 *  <Address_in_top> ... <Address_in_parent_module>
 * The address will be decoded to a binary format
 *
 * For each configuration bit, the data_in for the frame-based decoders will be 
 * the same as the configuration bit in bitstream manager.
 *******************************************************************/
static 
void rec_build_module_fabric_dependent_frame_bitstream(const BitstreamManager& bitstream_manager,
                                                       const std::vector<ConfigBlockId>& parent_blocks,
                                                       const ModuleManager& module_manager,
                                                       const std::vector<ModuleId>& parent_modules,
                                                       const std::vector<size_t>& addr_code,
                                                       FabricBitstream& fabric_bitstream) {

  /* Depth-first search: if we have any children in the parent_block, 
   * we dive to the next level first! 
   */
  if (0 < bitstream_manager.block_children(parent_blocks.back()).size()) {
    const ConfigBlockId& parent_block = parent_blocks.back();
    const ModuleId& parent_module = parent_modules.back();

    size_t num_configurable_children = module_manager.configurable_children(parent_modules.back()).size();

    bool add_addr_code = true;
    ModuleId decoder_module = ModuleId::INVALID();

    /* Early exit if there is no configurable children */
    if (0 == num_configurable_children) {
      return;
    }

    /* For only 1 configurable child, there is not frame decoder need, we can pass on addr code directly */
    if (1 == num_configurable_children) {
      add_addr_code = false;
    } else {
    /* For more than 2 children, there is a decoder in the tail of the list
     * We will not decode that, but will access the address size from that module
     * So, we reduce the number of children by 1
     */
      VTR_ASSERT(2 < num_configurable_children);
      num_configurable_children--;
      decoder_module = module_manager.configurable_children(parent_module).back();
    }

    for (size_t child_id = 0; child_id < num_configurable_children; ++child_id) {
      ModuleId child_module = module_manager.configurable_children(parent_modules.back())[child_id]; 
      size_t child_instance = module_manager.configurable_child_instances(parent_module)[child_id]; 
      /* Get the instance name and ensure it is not empty */
      std::string instance_name = module_manager.instance_name(parent_module, child_module, child_instance);
       
      /* Find the child block that matches the instance name! */ 
      ConfigBlockId child_block = bitstream_manager.find_child_block(parent_block, instance_name); 
      /* We must have one valid block id! */
      if (true != bitstream_manager.valid_block_id(child_block))
      VTR_ASSERT(true == bitstream_manager.valid_block_id(child_block));

      /* Pass on the list of blocks, modules and address lists */
      std::vector<ConfigBlockId> child_blocks = parent_blocks;
      child_blocks.push_back(child_block);

      std::vector<ModuleId> child_modules = parent_modules;
      child_modules.push_back(child_module);

      /* Set address, apply binary conversion from the first to the last element in the address list */
      std::vector<size_t> child_addr_code = addr_code;

      if (true == add_addr_code) { 
        /* Find the address port from the decoder module */
        const ModulePortId& decoder_addr_port_id = module_manager.find_module_port(decoder_module, std::string(DECODER_ADDRESS_PORT_NAME));
        const BasicPort& decoder_addr_port = module_manager.module_port(decoder_module, decoder_addr_port_id);
        std::vector<size_t> addr_bits_vec = itobin_vec(child_id, decoder_addr_port.get_width());
        child_addr_code.insert(child_addr_code.end(), addr_bits_vec.begin(), addr_bits_vec.end());
      }

      /* Go recursively */
      rec_build_module_fabric_dependent_frame_bitstream(bitstream_manager, child_blocks,
                                                        module_manager, child_modules,
                                                        child_addr_code,
                                                        fabric_bitstream);
    }
    /* Ensure that there should be no configuration bits in the parent block */
    VTR_ASSERT(0 == bitstream_manager.block_bits(parent_block).size());
  }

  /* Note that, reach here, it means that this is a leaf node. 
   * We add the configuration bits to the fabric_bitstream,
   * And then, we can return
   */
  for (const ConfigBitId& config_bit : bitstream_manager.block_bits(parent_blocks.back())) {
    const FabricBitId& fabric_bit = fabric_bitstream.add_bit(config_bit);

    /* Set address */
    fabric_bitstream.set_bit_address(fabric_bit, addr_code);
    
    /* Set data input */
    fabric_bitstream.set_bit_din(fabric_bit, bitstream_manager.bit_value(config_bit));
  }
}

/********************************************************************
 * Main function to build a fabric-dependent bitstream
 * by considering the configuration protocol types 
 *******************************************************************/
static 
void build_module_fabric_dependent_bitstream(const ConfigProtocol& config_protocol,
                                             const BitstreamManager& bitstream_manager,
                                             const ConfigBlockId& top_block,
                                             const ModuleManager& module_manager,
                                             const ModuleId& top_module,
                                             FabricBitstream& fabric_bitstream) {

  switch (config_protocol.type()) {
  case CONFIG_MEM_STANDALONE: {
    rec_build_module_fabric_dependent_chain_bitstream(bitstream_manager, top_block,
                                                      module_manager, top_module, 
                                                      fabric_bitstream);
    break;
  }
  case CONFIG_MEM_SCAN_CHAIN: { 
    rec_build_module_fabric_dependent_chain_bitstream(bitstream_manager, top_block,
                                                      module_manager, top_module, 
                                                      fabric_bitstream);
    fabric_bitstream.reverse();
    break;
  }
  case CONFIG_MEM_MEMORY_BANK: { 
    break;
  }
  case CONFIG_MEM_FRAME_BASED: {
    rec_build_module_fabric_dependent_frame_bitstream(bitstream_manager,
                                                      std::vector<ConfigBlockId>(1, top_block),
                                                      module_manager,
                                                      std::vector<ModuleId>(1, top_module),
                                                      std::vector<size_t>(),
                                                      fabric_bitstream);
    break;
  }
  default:
    VTR_LOGF_ERROR(__FILE__, __LINE__,
                   "Invalid SRAM organization.\n");
    exit(1);
  }

  /* Time-consuming sanity check: Uncomment these codes only for debugging!!!
   * Check which configuration bits are not touched 
   */
  /*
  for (const ConfigBitId& config_bit : bitstream_manager.bits()) {
    std::vector<ConfigBitId>::iterator it = std::find(fabric_bitstream.begin(), fabric_bitstream.end(), config_bit);
    if (it == fabric_bitstream.end()) {
      std::vector<ConfigBlockId> block_hierarchy = find_bitstream_manager_block_hierarchy(bitstream_manager, bitstream_manager.bit_parent_block(config_bit)); 
      std::string block_hierarchy_name;
      for (const ConfigBlockId& temp_block : block_hierarchy) {
        block_hierarchy_name += std::string("/") + bitstream_manager.block_name(temp_block);
      }
      vpr_printf(TIO_MESSAGE_INFO, 
                 "bit (parent_block = %s) is not touched!\n", 
                 block_hierarchy_name.c_str());
    }
  }
   */

  /* Ensure our fabric bitstream is in the same size as device bistream */
  VTR_ASSERT(bitstream_manager.bits().size() == fabric_bitstream.bits().size());
}

/********************************************************************
 * A top-level function re-organizes the bitstream for a specific 
 * FPGA fabric, where configuration bits are organized in the sequence
 * that can be directly loaded to the FPGA configuration protocol.
 * Support:
 * 1. Configuration chain
 * 2. Memory decoders
 * This function does NOT modify the bitstream database
 * Instead, it builds a vector of ids for configuration bits in bitstream manager
 *
 * This function can be called ONLY after the function build_device_bitstream() 
 * Note that this function does NOT decode bitstreams from circuit implementation
 * It was done in the function build_device_bitstream() 
 *******************************************************************/
FabricBitstream build_fabric_dependent_bitstream(const BitstreamManager& bitstream_manager,
                                                 const ModuleManager& module_manager,
                                                 const ConfigProtocol& config_protocol,
                                                 const bool& verbose) {
  FabricBitstream fabric_bitstream; 

  vtr::ScopedStartFinishTimer timer("\nBuild fabric dependent bitstream\n");

  /* Get the top module name in module manager, which is our starting point */
  std::string top_module_name = generate_fpga_top_module_name();
  ModuleId top_module = module_manager.find_module(top_module_name);
  VTR_ASSERT(true == module_manager.valid_module_id(top_module));

  /* Find the top block in bitstream manager, which has not parents */
  std::vector<ConfigBlockId> top_block = find_bitstream_manager_top_blocks(bitstream_manager);
  /* Make sure we have only 1 top block and its name matches the top module */
  VTR_ASSERT(1 == top_block.size());
  VTR_ASSERT(0 == top_module_name.compare(bitstream_manager.block_name(top_block[0])));

  build_module_fabric_dependent_bitstream(config_protocol,
                                          bitstream_manager, top_block[0],
                                          module_manager, top_module, 
                                          fabric_bitstream);

  VTR_LOGV(verbose,
           "Built %lu configuration bits for fabric\n",
           fabric_bitstream.bits().size());

  return fabric_bitstream;
}

} /* end namespace openfpga */