/*
  Copyright:    © SIL International.
  Description:  This is an implementation of the LDML keyboard spec 3.0.
  Create Date:  5 Aug 2022
  Authors:      Marc Durdin (MD)
*/

#include <fstream>
#include "ldml/ldml_processor.hpp"
#include "state.hpp"
#include "kmx_file.h"
#include "kmx/kmx_plus.h"
#include "kmx/kmx_xstring.h"
#include "ldml/keyboardprocessor_ldml.h"
#include "kmx/kmx_file_validator.hpp"
#include "debuglog.h"
#include <assert.h>

namespace {
  constexpr km_kbp_attr const engine_attrs = {
    256,
    KM_KBP_LIB_CURRENT,
    KM_KBP_LIB_AGE,
    KM_KBP_LIB_REVISION,
    KM_KBP_TECH_LDML,
    "SIL International"
  };
}

// using km::kbp::kmx::ShouldDebug; // for DebugLog

namespace km {
namespace kbp {


ldml_processor::ldml_processor(path const & kb_path, const std::vector<uint8_t> &data)
: abstract_processor(
    keyboard_attributes(kb_path.stem(), KM_KBP_LMDL_PROCESSOR_VERSION, kb_path.parent(), {})
  ), _valid(false), transforms(), bksp_transforms(), keys()
{

  if(data.size() <= sizeof(kmx::COMP_KEYBOARD_EX)) {
    DebugLog("data.size %zu too small", data.size());
    return;
  }

//   // Locate the structs here, but still retain ptrs to the raw structs.
  kmx::KMX_FileValidator* comp_keyboard = (kmx::KMX_FileValidator*)data.data();

  // Perform the standard validation
  if(!comp_keyboard->VerifyKeyboard(data.size())) {
    DebugLog("VerifyKeyboard() returned false");
    return;
  }

  kmx::kmx_plus kplus(comp_keyboard, data.size()); // slices to a COMP_KEYBOARD

  if(!kplus.is_valid()) {
    DebugLog("kmx_plus.is_valid is false");
    return;
  }

  // Now, if we have keys, use them.
  if (kplus.key2 != nullptr) {
    // read all keys into array
    for (KMX_DWORD i=0; i<kplus.key2->kmapCount; i++) {
      std::u16string str;
      auto kmapEntry = kplus.key2Helper.getKmap(i);
      assert(kmapEntry != nullptr);
      // now look up the key
      auto keyEntry = kplus.key2Helper.getKeys(kmapEntry->key);
      assert(keyEntry != nullptr);

      if (keyEntry->flags && LDML_KEYS_KEY_FLAGS_EXTEND) {
        if (nullptr == kplus.strs) {
          DebugLog("for keys: kplus.strs == nullptr"); // need a string table to get strings
          assert(false);
          return;
        }
        str = kplus.strs->get(keyEntry->to);
      } else {
        str = keyEntry->get_string();
      }
      keys.add((km_kbp_virtual_key)kmapEntry->vkey, (uint16_t)kmapEntry->mod, str);
    }
  } // else: no keys! but still valid. Just, no keys.

  // load transforms
  if (kplus.tran != nullptr && kplus.tran->groupCount > 0) {
    transforms.reset(km::kbp::ldml::load_transform_groups(kplus, kplus.tran, kplus.tranHelper));
    if (!transforms) {
      DebugLog("Failed to load tran transforms");
      return; // failed to load
    }
  }

  // load transforms
  if (kplus.bksp != nullptr && kplus.bksp->groupCount > 0) {
    bksp_transforms.reset(km::kbp::ldml::load_transform_groups(kplus, kplus.bksp, kplus.bkspHelper));
    if (!transforms) {
      DebugLog("Failed to load bksp transforms");
      return; // failed to load
    }
  }
  // Only valid if we reach here
  DebugLog("_valid = true");
  _valid = true;
}

bool ldml_processor::is_kmxplus_file(path const & kb_path, std::vector<uint8_t>& data) {
// TODO-LDML: we should refactor all the core components to delegate file loading
//            to the Engine, which requires an API change, but this makes delivery
//            of keyboard files more flexible under more WASM.

  std::ifstream file(static_cast<std::string>(kb_path), std::ios::binary | std::ios::ate);
  if(!file.good()) {
    return false;
  }
  const std::streamsize size = file.tellg();
  if(size >= KMX_MAX_ALLOWED_FILE_SIZE) {
    return false;
  }

  file.seekg(0, std::ios::beg);

  data.resize((size_t)size);
  if(!file.read((char *) data.data(), size)) {
    return false;
  }

  file.close();

  const kmx::PCOMP_KEYBOARD comp_keyboard = (kmx::PCOMP_KEYBOARD)data.data();

  if(comp_keyboard->dwIdentifier != KMX_DWORD(FILEID_COMPILED)) {
    return false;
  }

  if(comp_keyboard->dwFileVersion < VERSION_160 || (comp_keyboard->dwFlags & KF_KMXPLUS) == 0) {
    return false;
  }

  // A KMXPlus file is in the buffer (although more validation is required and will
  // be done in the constructor)
  return true;
}

km_kbp_status
ldml_processor::process_queued_actions(
  km_kbp_state *state
) {
  assert(state);
  if (!state)
    return KM_KBP_STATUS_INVALID_ARGUMENT;
  // TODO Implement
  return KM_KBP_STATUS_OK;
}

bool ldml_processor::queue_action(
  km_kbp_state * state,
  km_kbp_action_item const* action_item
)
{
  assert(state);
  assert(action_item);
  if ((!state) || (!action_item))
    return false;
  return false;
}

km_kbp_status
ldml_processor::process_event(
  km_kbp_state *state,
  km_kbp_virtual_key vk,
  uint16_t modifier_state,
  uint8_t is_key_down,
  uint16_t /*event_flags*/ // TODO-LDML: unused... for now...
) {
  assert(state);
  if (!state)
    return KM_KBP_STATUS_INVALID_ARGUMENT;

  if (!is_key_down) {
    // TODO: Implement caps lock handling
    state->actions().clear();
    state->actions().commit();
    return KM_KBP_STATUS_OK;
  }

  try {
    // At the start of every process_event always clear the action_items
    state->actions().clear();

    switch (vk) {
    case KM_KBP_VKEY_BKSP:
      {
        if (!!bksp_transforms) {
          // TODO-LDML: process bksp
          // std::u16string outputString;
          // // don't bother if no backspace transforms!
          // // TODO-LDML: unroll ctxt into a str
          // std::u16string ctxtstr;
          // for (size_t i = 0; i < ctxt.size(); i++) {
          //   ctxtstr.append(ctxt[i]);
          // }
          // const size_t matchedContext = transforms->apply(ctxtstr, outputString);
        }
        KMX_DWORD last_char = 0UL;
        // attempt to get the last char
        auto end = state->context().rbegin();
        if(end != state->context().rend()) {
          if((*end).type == KM_KBP_CT_CHAR) {
            last_char = (*end).character;
          }
        }
        if (last_char == 0UL) {
          // couldn't find the last char
          state->actions().push_backspace(KM_KBP_BT_UNKNOWN);
        } else {
          state->actions().push_backspace(KM_KBP_BT_CHAR, last_char);
        }
        state->context().pop_back();
      }
      break;
    default:
      // from kmx_processor.cpp
      // Construct a context buffer from the items up until the last KM_KBP_CT_MARKER marker
      ldml::string_list ctxt;
      auto cp = state->context();
      // We're only interested in as much of the context as is a KM_KBP_CT_CHAR.
      // This will stop at the KM_KBP_CT_MARKER type.
      uint8_t last_type = KM_KBP_BT_UNKNOWN;
      for (auto c = cp.rbegin(); c != cp.rend(); c++) {
        last_type = c->type;
        if (last_type != KM_KBP_BT_CHAR) {
          break;
        }
        km::kbp::kmx::char16_single buf;
        const int len = km::kbp::kmx::Utf32CharToUtf16(c->character, buf);
        const std::u16string str(buf.ch, len);
        ctxt.push_front(str); // prepend to string
      }
      if (last_type != KM_KBP_BT_MARKER) {
        // There was no beginning-of-translation marker.
        //Add one.
        state->context().push_marker(0x0);
        state->actions().push_marker(0x0);
      }
      // Look up the key
      const std::u16string str = keys.lookup(vk, modifier_state);
      if (str.empty()) {
        // not found
        state->actions().commit(); // finish up and
        return KM_KBP_STATUS_OK; // Nothing to do- no key
      }
      const std::u32string str32 = kmx::u16string_to_u32string(str);
      for(size_t i=0; i<str32.length(); i++) {
        state->context().push_character(str32[i]);
        state->actions().push_character(str32[i]);
      }
      // add the newly added char
      ctxt.push_back(str);
      // Now process transforms
      std::u16string outputString;
      // Process the transforms
      if (!!transforms) {

        // TODO-LDML: unroll ctxt into a str
        std::u16string ctxtstr;
        for (size_t i = 0; i < ctxt.size(); i++) {
          ctxtstr.append(ctxt[i]);
        }
        const size_t matchedContext = transforms->apply(ctxtstr, outputString);

        if (matchedContext > 0) {
          // Found something.
          // Now, clear out the old context
          for (size_t i = 0; i < matchedContext; i++) {
            state->context().pop_back();  // Pop off last
            auto deletedChar = ctxt[ctxt.size() - i - 1][0];
            state->actions().push_backspace(KM_KBP_BT_CHAR, deletedChar);  // Cause prior char to be removed
          }
          // Now, add in the updated text
          const std::u32string outstr32 = kmx::u16string_to_u32string(outputString);
          for (size_t i = 0; i < outstr32.length(); i++) {
            state->context().push_character(outstr32[i]);
            state->actions().push_character(outstr32[i]);
          }
          // Add a marker so we don't retransform this text.
          state->context().push_marker(0x0);
          state->actions().push_marker(0x0);
        }
      }
    }
    state->actions().commit();
  } catch (std::bad_alloc &) {
    state->actions().clear();
    return KM_KBP_STATUS_NO_MEM;
  }

  return KM_KBP_STATUS_OK;
}

km_kbp_attr const & ldml_processor::attributes() const {
  return engine_attrs;
}

km_kbp_keyboard_key  * ldml_processor::get_key_list() const {
  km_kbp_keyboard_key* key_list = new km_kbp_keyboard_key(KM_KBP_KEYBOARD_KEY_LIST_END);
  return key_list;
}

km_kbp_keyboard_imx  * ldml_processor::get_imx_list() const {
  km_kbp_keyboard_imx* imx_list = new km_kbp_keyboard_imx(KM_KBP_KEYBOARD_IMX_END);
  return imx_list;
}

km_kbp_context_item * ldml_processor::get_intermediate_context() {
  km_kbp_context_item *citems = new km_kbp_context_item(KM_KBP_CONTEXT_ITEM_END);
  return citems;
}

km_kbp_status ldml_processor::validate() const {
  return _valid ? KM_KBP_STATUS_OK : KM_KBP_STATUS_INVALID_KEYBOARD;
}

} // namespace kbp
} // namespace km