#include "../include/ts.h"
#include "../include/editor.h"
#include "../include/knot.h"
#include "../include/maps.h"
#include <algorithm>
#include <cstdint>
#include <fstream>
#include <functional>
#include <string>
#include <unordered_map>

std::unordered_map<std::string, pcre2_code *> regex_cache;

void clear_regex_cache() {
  for (auto &kv : regex_cache)
    pcre2_code_free(kv.second);
  regex_cache.clear();
}

pcre2_code *get_re(const std::string &pattern) {
  auto it = regex_cache.find(pattern);
  if (it != regex_cache.end())
    return it->second;
  int errornum;
  PCRE2_SIZE erroffset;
  pcre2_code *re =
      pcre2_compile((PCRE2_SPTR)pattern.c_str(), PCRE2_ZERO_TERMINATED, 0,
                    &errornum, &erroffset, nullptr);
  regex_cache[pattern] = re;
  return re;
}

TSQuery *load_query(const char *query_path, TSSetBase *set) {
  const TSLanguage *lang = set->language;
  std::ifstream file(query_path, std::ios::in | std::ios::binary);
  if (!file.is_open())
    return nullptr;
  std::string highlight_query((std::istreambuf_iterator<char>(file)),
                              std::istreambuf_iterator<char>());
  int errornumber = 0;
  PCRE2_SIZE erroroffset = 0;
  pcre2_code *re = pcre2_compile(
      (PCRE2_SPTR) R"((@[A-Za-z0-9_.]+)|(;; \#[0-9a-fA-F]{6} \#[0-9a-fA-F]{6} [01] [01] [01] \d+)|(;; !(\w+)))",
      PCRE2_ZERO_TERMINATED, 0, &errornumber, &erroroffset, nullptr);
  if (!re)
    return nullptr;
  pcre2_match_data *match_data =
      pcre2_match_data_create_from_pattern(re, nullptr);
  std::map<std::string, int> capture_name_cache;
  Highlight *c_hl = nullptr;
  Language c_lang = {"unknown", nullptr, 0};
  int i = 0;
  PCRE2_SIZE offset = 0;
  PCRE2_SIZE subject_length = highlight_query.size();
  while (offset < subject_length) {
    int rc = pcre2_match(re, (PCRE2_SPTR)highlight_query.c_str(),
                         subject_length, offset, 0, match_data, nullptr);
    if (rc <= 0)
      break;
    PCRE2_SIZE *ovector = pcre2_get_ovector_pointer(match_data);
    std::string mct =
        highlight_query.substr(ovector[0], ovector[1] - ovector[0]);
    if (!mct.empty() && mct[0] == '@') {
      std::string capture_name = mct;
      if (!capture_name_cache.count(capture_name)) {
        if (c_hl) {
          set->query_map[i] = *c_hl;
          delete c_hl;
          c_hl = nullptr;
        }
        if (c_lang.fn != nullptr) {
          set->injection_map[i] = c_lang;
          c_lang = {"unknown", nullptr, 0};
        }
        capture_name_cache[capture_name] = i;
        i++;
      }
    } else if (mct.substr(0, 4) == ";; #") {
      if (c_hl)
        delete c_hl;
      c_hl = new Highlight();
      c_hl->fg = HEX(mct.substr(4, 6));
      c_hl->bg = HEX(mct.substr(12, 6));
      int bold = std::stoi(mct.substr(19, 1));
      int italic = std::stoi(mct.substr(21, 1));
      int underline = std::stoi(mct.substr(23, 1));
      c_hl->priority = std::stoi(mct.substr(25));
      c_hl->flags = (bold ? CF_BOLD : 0) | (italic ? CF_ITALIC : 0) |
                    (underline ? CF_UNDERLINE : 0);
    } else if (mct.substr(0, 4) == ";; !") {
      auto it = kLanguages.find(mct.substr(4));
      if (it != kLanguages.end())
        c_lang = it->second;
      else
        c_lang = {"unknown", nullptr, 0};
    }
    offset = ovector[1];
  }
  if (c_hl)
    delete c_hl;
  pcre2_match_data_free(match_data);
  pcre2_code_free(re);
  uint32_t error_offset = 0;
  TSQueryError error_type = (TSQueryError)0;
  TSQuery *q = ts_query_new(lang, highlight_query.c_str(),
                            (uint32_t)highlight_query.length(), &error_offset,
                            &error_type);
  if (!q)
    log("Failed to create TSQuery at offset %u, error type %d", error_offset,
        (int)error_type);
  return q;
}

static inline const TSNode *find_capture_node(const TSQueryMatch &match,
                                              uint32_t capture_id) {
  for (uint32_t i = 0; i < match.capture_count; i++)
    if (match.captures[i].index == capture_id)
      return &match.captures[i].node;
  return nullptr;
}

static inline std::string node_text(uint32_t start, uint32_t end,
                                    Knot *source) {
  char *text = read(source, start, end - start);
  std::string final = std::string(text, end - start);
  free(text);
  return final;
}

bool ts_predicate(TSQuery *query, const TSQueryMatch &match,
                  std::function<std::string(const TSNode *)> subject_fn) {
  uint32_t step_count;
  const TSQueryPredicateStep *steps =
      ts_query_predicates_for_pattern(query, match.pattern_index, &step_count);
  if (!steps || step_count != 4)
    return true;
  std::string command;
  std::string regex_txt;
  uint32_t subject_id = 0;
  for (uint32_t i = 0; i < step_count; i++) {
    const TSQueryPredicateStep *step = &steps[i];
    if (step->type == TSQueryPredicateStepTypeDone)
      break;
    switch (step->type) {
    case TSQueryPredicateStepTypeString: {
      uint32_t length = 0;
      const char *s =
          ts_query_string_value_for_id(query, step->value_id, &length);
      if (i == 0)
        command.assign(s, length);
      else
        regex_txt.assign(s, length);
      break;
    }
    case TSQueryPredicateStepTypeCapture: {
      subject_id = step->value_id;
      break;
    }
    case TSQueryPredicateStepTypeDone:
      break;
    }
  }
  const TSNode *node = find_capture_node(match, subject_id);
  pcre2_code *re = get_re(regex_txt);
  std::string subject = subject_fn(node);
  pcre2_match_data *md = pcre2_match_data_create_from_pattern(re, nullptr);
  int rc = pcre2_match(re, (PCRE2_SPTR)subject.c_str(), subject.size(), 0, 0,
                       md, nullptr);
  pcre2_match_data_free(md);
  bool ok = (rc >= 0);
  return (command == "match?" ? ok : !ok);
}

const char *read_ts(void *payload, uint32_t byte_index, TSPoint,
                    uint32_t *bytes_read) {
  Editor *editor = (Editor *)payload;
  if (byte_index >= editor->root->char_count) {
    *bytes_read = 0;
    return "";
  }
  return leaf_from_offset(editor->root, byte_index, bytes_read);
}

void ts_collect_spans(Editor *editor) {
  static int parse_counter = 0;
  if (!editor->ts.parser || !editor->root || !editor->ts.query)
    return;
  const bool injections_enabled = editor->root->char_count < (1024 * 32);
  for (auto &inj : editor->ts.injections)
    inj.second.ranges.clear();
  TSInput tsinput{
      .payload = editor,
      .read = read_ts,
      .encoding = TSInputEncodingUTF8,
      .decode = nullptr,
  };
  std::vector<TSInputEdit> edits;
  TSInputEdit edit;
  if (!editor->edit_queue.empty()) {
    while (editor->edit_queue.pop(edit))
      edits.push_back(edit);
    if (editor->ts.tree) {
      for (auto &e : edits)
        ts_tree_edit(editor->ts.tree, &e);
    }
    for (auto &inj : editor->ts.injections) {
      if (inj.second.tree) {
        for (auto &e : edits) {
          TSInputEdit inj_edit = e;
          for (auto &r : inj.second.ranges) {
            if (e.start_byte >= r.start_byte && e.start_byte <= r.end_byte) {
              inj_edit.start_byte -= r.start_byte;
              inj_edit.old_end_byte -= r.start_byte;
              inj_edit.new_end_byte -= r.start_byte;
            }
          }
          ts_tree_edit(inj.second.tree, &inj_edit);
        }
      }
    }
  } else if (editor->ts.tree && parse_counter < 64) {
    parse_counter++;
    return;
  }
  parse_counter = 0;
  editor->spans.mid_parse = true;
  std::shared_lock lock(editor->knot_mtx);
  TSTree *tree = ts_parser_parse(editor->ts.parser, editor->ts.tree, tsinput);
  if (!tree)
    return;
  if (editor->ts.tree)
    ts_tree_delete(editor->ts.tree);
  editor->ts.tree = tree;
  lock.unlock();
  std::vector<Span> new_spans;
  new_spans.reserve(4096);
  struct PendingRanges {
    std::vector<TSRange> ranges;
    TSSet *tsset = nullptr;
  };
  struct WorkItem {
    TSSetBase *tsset;
    TSTree *tree;
    int depth;
  };
  const int kMaxInjectionDepth = 4;
  std::vector<WorkItem> work;
  work.push_back(
      {reinterpret_cast<TSSetBase *>(&editor->ts), editor->ts.tree, 0});
  auto overlaps = [](const Span &s, const TSRange &r) {
    return !(s.end <= r.start_byte || s.start >= r.end_byte);
  };
  auto remove_overlapping_spans = [&](const std::vector<TSRange> &ranges) {
    if (ranges.empty())
      return;
    new_spans.erase(
        std::remove_if(new_spans.begin(), new_spans.end(),
                       [&](const Span &sp) {
                         return std::any_of(
                             ranges.begin(), ranges.end(),
                             [&](const TSRange &r) { return overlaps(sp, r); });
                       }),
        new_spans.end());
  };
  while (!work.empty()) {
    WorkItem item = work.back();
    work.pop_back();
    TSQuery *q = item.tsset->query;
    if (!q)
      continue;
    TSQueryCursor *cursor = ts_query_cursor_new();
    ts_query_cursor_exec(cursor, q, ts_tree_root_node(item.tsset->tree));
    std::unordered_map<std::string, PendingRanges> pending_injections;
    TSQueryMatch match;
    while (ts_query_cursor_next_match(cursor, &match)) {
      auto subject_fn = [&](const TSNode *node) -> std::string {
        uint32_t start = ts_node_start_byte(*node);
        uint32_t end = ts_node_end_byte(*node);
        return node_text(start, end, editor->root);
      };
      if (!ts_predicate(q, match, subject_fn))
        continue;
      for (uint32_t i = 0; i < match.capture_count; i++) {
        TSQueryCapture cap = match.captures[i];
        uint32_t start = ts_node_start_byte(cap.node);
        uint32_t end = ts_node_end_byte(cap.node);
        if (Highlight *hl = safe_get(item.tsset->query_map, cap.index))
          new_spans.push_back({start, end, hl});
        if (!injections_enabled)
          continue;
        if (Language *inj_lang =
                safe_get(item.tsset->injection_map, cap.index)) {
          auto &pending = pending_injections[inj_lang->name];
          TSSet &tsset =
              editor->ts.injections.try_emplace(inj_lang->name).first->second;
          if (!tsset.parser) {
            tsset.lang = inj_lang->name;
            tsset.parser = ts_parser_new();
            ts_parser_set_language(tsset.parser, inj_lang->fn());
            tsset.language = inj_lang->fn();
            tsset.query_file =
                get_exe_dir() + "/../grammar/" + inj_lang->name + ".scm";
            tsset.query = load_query(tsset.query_file.c_str(), &tsset);
          }
          pending.tsset = &tsset;
          pending.ranges.push_back(TSRange{
              ts_node_start_point(cap.node),
              ts_node_end_point(cap.node),
              start,
              end,
          });
        }
      }
    }
    ts_query_cursor_delete(cursor);
    if (injections_enabled && item.depth < kMaxInjectionDepth) {
      for (auto &[lang_name, pending] : pending_injections) {
        TSSet *tsset = pending.tsset;
        if (!tsset || pending.ranges.empty() || !tsset->parser || !tsset->query)
          continue;
        tsset->ranges = std::move(pending.ranges);
        remove_overlapping_spans(tsset->ranges);
        ts_parser_set_included_ranges(tsset->parser, tsset->ranges.data(),
                                      tsset->ranges.size());
        lock.lock();
        TSTree *tree = ts_parser_parse(tsset->parser, tsset->tree, tsinput);
        if (!tree)
          continue;
        if (tsset->tree)
          ts_tree_delete(tsset->tree);
        tsset->tree = tree;
        lock.unlock();
        work.push_back({reinterpret_cast<TSSetBase *>(tsset), tsset->tree,
                        item.depth + 1});
      }
    }
  }
  std::pair<uint32_t, int64_t> span_edit;
  while (editor->spans.edits.pop(span_edit))
    apply_edit(new_spans, span_edit.first, span_edit.second);
  std::sort(new_spans.begin(), new_spans.end());
  std::unique_lock span_mtx(editor->spans.mtx);
  editor->spans.mid_parse = false;
  editor->spans.spans.swap(new_spans);
}