#pragma once

#include "fesa/Core/Core.hpp"
#include "fesa/Util/Util.hpp"

#include <algorithm>
#include <array>
#include <cmath>
#include <fstream>
#include <initializer_list>
#include <map>
#include <optional>
#include <set>
#include <sstream>
#include <string>
#include <vector>

namespace fesa {

struct KeywordLine {
  std::string name;
  std::map<std::string, std::string> parameters;
  std::set<std::string> flags;
};

inline KeywordLine parseKeywordLine(const std::string& line) {
  KeywordLine keyword;
  std::vector<std::string> pieces = splitCsv(line.substr(1));
  if (pieces.empty()) {
    return keyword;
  }
  keyword.name = lower(trim(pieces.front()));
  for (std::size_t i = 1; i < pieces.size(); ++i) {
    const std::string piece = trim(pieces[i]);
    if (piece.empty()) {
      continue;
    }
    const auto eq = piece.find('=');
    if (eq == std::string::npos) {
      keyword.flags.insert(lower(piece));
    } else {
      keyword.parameters[lower(trim(piece.substr(0, eq)))] = trim(piece.substr(eq + 1));
    }
  }
  return keyword;
}

struct ParseResult {
  Domain domain;
  std::vector<Diagnostic> diagnostics;

  bool ok() const {
    return !hasError(diagnostics);
  }
};

class AbaqusInputParser {
 public:
  ParseResult parseString(const std::string& text, const std::string& file_name = "<memory>") const {
    ParseResult result;
    std::istringstream stream(text);
    std::string line;
    KeywordLine current;
    std::string current_material_key;
    KeywordLine current_shell_section;
    LocalIndex line_number = 0;
    LocalIndex current_keyword_line = 0;

    auto add_error = [&](const std::string& code, const std::string& message) {
      const LocalIndex source_line = current_keyword_line == 0 ? line_number : current_keyword_line;
      result.diagnostics.push_back({Severity::Error, code, message, {file_name, source_line, current.name}});
    };
    auto is_allowed = [](const std::string& value, std::initializer_list<const char*> allowed_values) {
      return std::any_of(allowed_values.begin(), allowed_values.end(), [&](const char* allowed) {
        return value == allowed;
      });
    };
    auto reject_unsupported_controls = [&](std::initializer_list<const char*> allowed_parameters,
                                           std::initializer_list<const char*> allowed_flags) {
      for (const auto& [parameter, value] : current.parameters) {
        (void)value;
        if (!is_allowed(parameter, allowed_parameters)) {
          const LocalIndex source_line = current_keyword_line == 0 ? line_number : current_keyword_line;
          result.diagnostics.push_back({Severity::Error,
                                        "FESA-PARSE-UNSUPPORTED-PARAMETER",
                                        "Unsupported *" + current.name + " parameter: " + parameter,
                                        {file_name, source_line, current.name}});
        }
      }
      for (const std::string& flag : current.flags) {
        if (!is_allowed(flag, allowed_flags)) {
          const LocalIndex source_line = current_keyword_line == 0 ? line_number : current_keyword_line;
          result.diagnostics.push_back({Severity::Error,
                                        "FESA-PARSE-UNSUPPORTED-PARAMETER",
                                        "Unsupported *" + current.name + " flag: " + flag,
                                        {file_name, source_line, current.name}});
        }
      }
    };

    while (std::getline(stream, line)) {
      ++line_number;
      line = trim(line);
      if (line.empty() || line.rfind("**", 0) == 0) {
        continue;
      }
      if (!line.empty() && line.front() == '*') {
        current_keyword_line = line_number;
        std::string keyword_line = line;
        while (!keyword_line.empty() && keyword_line.back() == ',') {
          std::string continuation;
          if (!std::getline(stream, continuation)) {
            break;
          }
          ++line_number;
          continuation = trim(continuation);
          if (continuation.empty() || continuation.rfind("**", 0) == 0) {
            continue;
          }
          keyword_line += continuation;
        }
        current = parseKeywordLine(keyword_line);
        if (current.name == "node") {
          reject_unsupported_controls({}, {});
          continue;
        }
        if (current.name == "element") {
          reject_unsupported_controls({"type", "elset"}, {});
          continue;
        }
        if (current.name == "nset") {
          reject_unsupported_controls({"nset"}, {"generate"});
          continue;
        }
        if (current.name == "elset") {
          reject_unsupported_controls({"elset"}, {"generate"});
          continue;
        }
        if (current.name == "elastic") {
          reject_unsupported_controls({}, {});
          continue;
        }
        if (current.name == "shell section") {
          reject_unsupported_controls({"elset", "material"}, {});
          current_shell_section = current;
          continue;
        }
        if (current.name == "boundary" || current.name == "cload" || current.name == "static") {
          reject_unsupported_controls({}, {});
          continue;
        }
        if (current.name == "material") {
          reject_unsupported_controls({"name"}, {});
          auto name_it = current.parameters.find("name");
          if (name_it == current.parameters.end() || trim(name_it->second).empty()) {
            add_error("FESA-PARSE-MATERIAL-NAME", "*Material requires NAME");
            current_material_key.clear();
            continue;
          }
          Material material;
          material.name = trim(name_it->second);
          current_material_key = Domain::key(material.name);
          if (result.domain.materials.count(current_material_key) != 0) {
            add_error("FESA-PARSE-DUPLICATE-MATERIAL", "Duplicate material: " + material.name);
          } else {
            result.domain.materials[current_material_key] = material;
          }
          continue;
        }
        if (current.name == "step") {
          reject_unsupported_controls({"name", "nlgeom"}, {});
          auto nlgeom = current.parameters.find("nlgeom");
          if (nlgeom != current.parameters.end() && lower(trim(nlgeom->second)) == "yes") {
            add_error("FESA-PARSE-UNSUPPORTED-NLGEOM", "NLGEOM=YES is not supported in Phase 1");
          }
          StepDefinition step;
          auto name_it = current.parameters.find("name");
          if (name_it != current.parameters.end() && !trim(name_it->second).empty()) {
            step.name = trim(name_it->second);
          }
          result.domain.steps.push_back(step);
          continue;
        }
        if (current.name == "end step") {
          reject_unsupported_controls({}, {});
          continue;
        }
        add_error("FESA-PARSE-UNSUPPORTED-KEYWORD", "Unsupported keyword: *" + current.name);
        continue;
      }

      const std::vector<std::string> fields = splitCsv(line);
      if (current.name == "node") {
        parseNode(fields, result, file_name, line_number);
      } else if (current.name == "element") {
        parseElement(fields, current, result, file_name, line_number);
      } else if (current.name == "nset") {
        parseNodeSet(fields, current, result, file_name, line_number);
      } else if (current.name == "elset") {
        parseElementSet(fields, current, result, file_name, line_number);
      } else if (current.name == "elastic") {
        parseElastic(fields, current_material_key, result, file_name, line_number);
      } else if (current.name == "shell section") {
        parseShellSection(fields, current_shell_section, result, file_name, line_number);
      } else if (current.name == "boundary") {
        parseBoundary(fields, result, file_name, line_number);
      } else if (current.name == "cload") {
        parseLoad(fields, result, file_name, line_number);
      }
    }

    if (result.domain.steps.empty()) {
      result.domain.steps.push_back({"Step-1", "linear_static"});
    }
    return result;
  }

  ParseResult parseFile(const std::string& path) const {
    std::ifstream input(path);
    std::ostringstream buffer;
    buffer << input.rdbuf();
    ParseResult result = parseString(buffer.str(), path);
    if (!input.good() && buffer.str().empty()) {
      result.diagnostics.push_back({Severity::Error, "FESA-PARSE-FILE", "Could not read input file", {path, 0, ""}});
    }
    return result;
  }

 private:
  static std::size_t effectiveFieldCount(const std::vector<std::string>& fields) {
    std::size_t count = fields.size();
    while (count > 0 && trim(fields[count - 1]).empty()) {
      --count;
    }
    return count;
  }

  static void parseNode(const std::vector<std::string>& fields,
                        ParseResult& result,
                        const std::string& file_name,
                        LocalIndex line) {
    if (effectiveFieldCount(fields) != 4) {
      result.diagnostics.push_back(
          {Severity::Error, "FESA-PARSE-NODE", "*Node data requires id,x,y,z", {file_name, line, "node"}});
      return;
    }
    auto id = parseInt64(fields[0]);
    auto x = parseReal(fields[1]);
    auto y = parseReal(fields[2]);
    auto z = parseReal(fields[3]);
    if (!id || !x || !y || !z) {
      result.diagnostics.push_back(
          {Severity::Error, "FESA-PARSE-NODE-NUMERIC", "Invalid node numeric field", {file_name, line, "node"}});
      return;
    }
    if (result.domain.nodes.count(*id) != 0) {
      result.diagnostics.push_back(
          {Severity::Error, "FESA-PARSE-DUPLICATE-NODE", "Duplicate node id", {file_name, line, "node"}});
      return;
    }
    result.domain.nodes[*id] = {*id, {*x, *y, *z}};
  }

  static void parseElement(const std::vector<std::string>& fields,
                           const KeywordLine& keyword,
                           ParseResult& result,
                           const std::string& file_name,
                           LocalIndex line) {
    auto type_it = keyword.parameters.find("type");
    if (type_it == keyword.parameters.end()) {
      result.diagnostics.push_back(
          {Severity::Error, "FESA-PARSE-ELEMENT-TYPE", "*Element requires TYPE", {file_name, line, "element"}});
      return;
    }
    const std::string type = lower(trim(type_it->second));
    if (type != "s4") {
      result.diagnostics.push_back({Severity::Error,
                                    "FESA-PARSE-UNSUPPORTED-ELEMENT",
                                    "Unsupported element type: " + type_it->second,
                                    {file_name, line, "element"}});
      return;
    }
    if (effectiveFieldCount(fields) != 5) {
      result.diagnostics.push_back({Severity::Error,
                                    "FESA-PARSE-ELEMENT",
                                    "S4 element requires id,n1,n2,n3,n4",
                                    {file_name, line, "element"}});
      return;
    }
    auto id = parseInt64(fields[0]);
    std::array<GlobalId, 4> nodes{};
    bool ok = id.has_value();
    for (int i = 0; i < 4; ++i) {
      auto node = parseInt64(fields[1 + static_cast<std::size_t>(i)]);
      ok = ok && node.has_value();
      if (node) {
        nodes[static_cast<std::size_t>(i)] = *node;
      }
    }
    if (!ok) {
      result.diagnostics.push_back(
          {Severity::Error, "FESA-PARSE-ELEMENT-NUMERIC", "Invalid element numeric field", {file_name, line, "element"}});
      return;
    }
    if (result.domain.elements.count(*id) != 0) {
      result.diagnostics.push_back(
          {Severity::Error, "FESA-PARSE-DUPLICATE-ELEMENT", "Duplicate element id", {file_name, line, "element"}});
      return;
    }
    Element element;
    element.id = *id;
    element.node_ids = nodes;
    auto elset_it = keyword.parameters.find("elset");
    if (elset_it != keyword.parameters.end()) {
      element.source_elset = trim(elset_it->second);
      auto& set = result.domain.element_sets[Domain::key(element.source_elset)];
      set.name = element.source_elset;
      addUnique(set.element_ids, *id);
    }
    result.domain.elements[*id] = element;
  }

  static void parseNodeSet(const std::vector<std::string>& fields,
                           const KeywordLine& keyword,
                           ParseResult& result,
                           const std::string& file_name,
                           LocalIndex line) {
    auto name_it = keyword.parameters.find("nset");
    if (name_it == keyword.parameters.end()) {
      result.diagnostics.push_back(
          {Severity::Error, "FESA-PARSE-NSET-NAME", "*Nset requires NSET", {file_name, line, "nset"}});
      return;
    }
    auto& set = result.domain.node_sets[Domain::key(name_it->second)];
    set.name = trim(name_it->second);
    parseSetData(fields, keyword.flags.count("generate") != 0, set.node_ids, result.diagnostics, file_name, line, "nset");
  }

  static void parseElementSet(const std::vector<std::string>& fields,
                              const KeywordLine& keyword,
                              ParseResult& result,
                              const std::string& file_name,
                              LocalIndex line) {
    auto name_it = keyword.parameters.find("elset");
    if (name_it == keyword.parameters.end()) {
      result.diagnostics.push_back(
          {Severity::Error, "FESA-PARSE-ELSET-NAME", "*Elset requires ELSET", {file_name, line, "elset"}});
      return;
    }
    auto& set = result.domain.element_sets[Domain::key(name_it->second)];
    set.name = trim(name_it->second);
    parseSetData(fields, keyword.flags.count("generate") != 0, set.element_ids, result.diagnostics, file_name, line, "elset");
  }

  static void parseSetData(const std::vector<std::string>& fields,
                           bool generate,
                           std::vector<GlobalId>& output,
                           std::vector<Diagnostic>& diagnostics,
                           const std::string& file_name,
                           LocalIndex line,
                           const std::string& keyword) {
    if (generate) {
      const std::size_t field_count = effectiveFieldCount(fields);
      if (field_count != 3) {
        diagnostics.push_back({Severity::Error,
                               "FESA-PARSE-GENERATE",
                               "Generated set requires first,last,increment",
                               {file_name, line, keyword}});
        return;
      }
      auto first = parseInt64(fields[0]);
      auto last = parseInt64(fields[1]);
      auto increment = parseInt64(fields[2]);
      if (!first || !last || !increment || *increment <= 0) {
        diagnostics.push_back(
            {Severity::Error, "FESA-PARSE-GENERATE", "Invalid generated set range", {file_name, line, keyword}});
        return;
      }
      for (GlobalId value : generatedRange(*first, *last, *increment)) {
        addUnique(output, value);
      }
      return;
    }
    const std::size_t field_count = effectiveFieldCount(fields);
    for (std::size_t i = 0; i < field_count; ++i) {
      const std::string& field = fields[i];
      if (trim(field).empty()) {
        continue;
      }
      auto value = parseInt64(field);
      if (!value) {
        diagnostics.push_back(
            {Severity::Error, "FESA-PARSE-SET-NUMERIC", "Invalid set id", {file_name, line, keyword}});
        return;
      }
      addUnique(output, *value);
    }
  }

  static void parseElastic(const std::vector<std::string>& fields,
                           const std::string& material_key,
                           ParseResult& result,
                           const std::string& file_name,
                           LocalIndex line) {
    if (material_key.empty() || result.domain.materials.count(material_key) == 0) {
      result.diagnostics.push_back(
          {Severity::Error, "FESA-PARSE-ELASTIC-MATERIAL", "*Elastic must follow *Material", {file_name, line, "elastic"}});
      return;
    }
    const std::size_t field_count = effectiveFieldCount(fields);
    if (field_count < 2) {
      result.diagnostics.push_back(
          {Severity::Error, "FESA-PARSE-ELASTIC", "*Elastic requires E,nu", {file_name, line, "elastic"}});
      return;
    }
    if (field_count > 2) {
      result.diagnostics.push_back({Severity::Error,
                                    "FESA-PARSE-ELASTIC-UNSUPPORTED",
                                    "Only isotropic E,nu elastic data is supported",
                                    {file_name, line, "elastic"}});
      return;
    }
    auto e = parseReal(fields[0]);
    auto nu = parseReal(fields[1]);
    if (!e || !nu || *e <= 0.0 || *nu <= -1.0 || *nu >= 0.5) {
      result.diagnostics.push_back({Severity::Error,
                                    "FESA-PARSE-ELASTIC-RANGE",
                                    "Invalid isotropic elastic constants",
                                    {file_name, line, "elastic"}});
      return;
    }
    result.domain.materials[material_key].elastic_modulus = *e;
    result.domain.materials[material_key].poisson_ratio = *nu;
  }

  static void parseShellSection(const std::vector<std::string>& fields,
                                const KeywordLine& keyword,
                                ParseResult& result,
                                const std::string& file_name,
                                LocalIndex line) {
    auto elset_it = keyword.parameters.find("elset");
    auto material_it = keyword.parameters.find("material");
    if (elset_it == keyword.parameters.end() || material_it == keyword.parameters.end()) {
      result.diagnostics.push_back({Severity::Error,
                                    "FESA-PARSE-SHELL-SECTION-PARAM",
                                    "*Shell Section requires ELSET and MATERIAL",
                                    {file_name, line, "shell section"}});
      return;
    }
    const std::size_t field_count = effectiveFieldCount(fields);
    if (field_count == 0) {
      result.diagnostics.push_back({Severity::Error,
                                    "FESA-PARSE-SHELL-SECTION",
                                    "*Shell Section requires thickness",
                                    {file_name, line, "shell section"}});
      return;
    }
    if (field_count > 1) {
      result.diagnostics.push_back({Severity::Error,
                                    "FESA-PARSE-SHELL-SECTION-UNSUPPORTED",
                                    "Only homogeneous shell thickness data is supported",
                                    {file_name, line, "shell section"}});
      return;
    }
    auto thickness = parseReal(fields[0]);
    if (!thickness || *thickness <= 0.0) {
      result.diagnostics.push_back({Severity::Error,
                                    "FESA-PARSE-SHELL-THICKNESS",
                                    "Shell thickness must be positive",
                                    {file_name, line, "shell section"}});
      return;
    }
    result.domain.shell_sections.push_back({trim(elset_it->second), trim(material_it->second), *thickness});
  }

  static void parseBoundary(const std::vector<std::string>& fields,
                            ParseResult& result,
                            const std::string& file_name,
                            LocalIndex line) {
    const std::size_t field_count = effectiveFieldCount(fields);
    if (field_count < 2) {
      result.diagnostics.push_back(
          {Severity::Error, "FESA-PARSE-BOUNDARY", "*Boundary requires target,first_dof", {file_name, line, "boundary"}});
      return;
    }
    if (field_count > 4) {
      result.diagnostics.push_back({Severity::Error,
                                    "FESA-PARSE-BOUNDARY-UNSUPPORTED",
                                    "Only direct zero-valued boundary data is supported",
                                    {file_name, line, "boundary"}});
      return;
    }
    auto first = parseInt64(fields[1]);
    auto last = field_count >= 3 && !fields[2].empty() ? parseInt64(fields[2]) : first;
    auto magnitude = field_count >= 4 && !fields[3].empty() ? parseReal(fields[3]) : std::optional<Real>(0.0);
    if (!first || !last || !magnitude || !dofFromAbaqus(static_cast<int>(*first)) ||
        !dofFromAbaqus(static_cast<int>(*last)) || *first > *last) {
      result.diagnostics.push_back({Severity::Error,
                                    "FESA-PARSE-BOUNDARY-DOF",
                                    "Invalid boundary DOF range",
                                    {file_name, line, "boundary"}});
      return;
    }
    if (std::fabs(*magnitude) > 0.0) {
      result.diagnostics.push_back({Severity::Error,
                                    "FESA-PARSE-BOUNDARY-NONZERO",
                                    "Nonzero prescribed displacement is not supported in Phase 1",
                                    {file_name, line, "boundary"}});
      return;
    }
    result.domain.boundary_conditions.push_back({trim(fields[0]), static_cast<int>(*first), static_cast<int>(*last), *magnitude});
  }

  static void parseLoad(const std::vector<std::string>& fields,
                        ParseResult& result,
                        const std::string& file_name,
                        LocalIndex line) {
    const std::size_t field_count = effectiveFieldCount(fields);
    if (field_count < 3) {
      result.diagnostics.push_back(
          {Severity::Error, "FESA-PARSE-CLOAD", "*Cload requires target,dof,magnitude", {file_name, line, "cload"}});
      return;
    }
    if (field_count > 3) {
      result.diagnostics.push_back({Severity::Error,
                                    "FESA-PARSE-CLOAD-UNSUPPORTED",
                                    "Only direct concentrated load data is supported",
                                    {file_name, line, "cload"}});
      return;
    }
    auto dof = parseInt64(fields[1]);
    auto magnitude = parseReal(fields[2]);
    if (!dof || !magnitude || !dofFromAbaqus(static_cast<int>(*dof))) {
      result.diagnostics.push_back(
          {Severity::Error, "FESA-PARSE-CLOAD-DOF", "Invalid concentrated load", {file_name, line, "cload"}});
      return;
    }
    result.domain.loads.push_back({trim(fields[0]), static_cast<int>(*dof), *magnitude});
  }
};

}  // namespace fesa