/* SPDX-License-Identifier: GPL-2.0-or-later
 * Copyright 2021 Blender Foundation. All rights reserved. */

/** \file
 * \ingroup gpu
 *
 * Shader source dependency builder that make possible to support #include directive inside the
 * shader files.
 */

#include <algorithm>
#include <iomanip>
#include <iostream>
#include <regex>
#include <sstream>

#include "BLI_ghash.h"
#include "BLI_map.hh"
#include "BLI_string_ref.hh"

#include "gpu_material_library.h"
#include "gpu_shader_create_info.hh"
#include "gpu_shader_dependency_private.h"

extern "C" {
#define SHADER_SOURCE(datatoc, filename, filepath) extern char datatoc[];
#include "glsl_compositor_source_list.h"
#include "glsl_draw_source_list.h"
#include "glsl_gpu_source_list.h"
#ifdef WITH_OCIO
#  include "glsl_ocio_source_list.h"
#endif
#undef SHADER_SOURCE
}

namespace blender::gpu {

using GPUSourceDictionnary = Map<StringRef, struct GPUSource *>;
using GPUFunctionDictionnary = Map<StringRef, struct GPUFunction *>;

struct GPUSource {
  StringRefNull fullpath;
  StringRefNull filename;
  StringRefNull source;
  Vector<GPUSource *> dependencies;
  bool dependencies_init = false;
  shader::BuiltinBits builtins = shader::BuiltinBits::NONE;
  std::string processed_source;

  GPUSource(const char *path,
            const char *file,
            const char *datatoc,
            GPUFunctionDictionnary *g_functions)
      : fullpath(path), filename(file), source(datatoc)
  {
    /* Scan for builtins. */
    /* FIXME: This can trigger false positive caused by disabled #if blocks. */
    /* TODO(fclem): Could be made faster by scanning once. */
    if (source.find("gl_FragCoord", 0) != StringRef::not_found) {
      builtins |= shader::BuiltinBits::FRAG_COORD;
    }
    if (source.find("gl_FrontFacing", 0) != StringRef::not_found) {
      builtins |= shader::BuiltinBits::FRONT_FACING;
    }
    if (source.find("gl_GlobalInvocationID", 0) != StringRef::not_found) {
      builtins |= shader::BuiltinBits::GLOBAL_INVOCATION_ID;
    }
    if (source.find("gl_InstanceID", 0) != StringRef::not_found) {
      builtins |= shader::BuiltinBits::INSTANCE_ID;
    }
    if (source.find("gl_LocalInvocationID", 0) != StringRef::not_found) {
      builtins |= shader::BuiltinBits::LOCAL_INVOCATION_ID;
    }
    if (source.find("gl_LocalInvocationIndex", 0) != StringRef::not_found) {
      builtins |= shader::BuiltinBits::LOCAL_INVOCATION_INDEX;
    }
    if (source.find("gl_NumWorkGroup", 0) != StringRef::not_found) {
      builtins |= shader::BuiltinBits::NUM_WORK_GROUP;
    }
    if (source.find("gl_PointCoord", 0) != StringRef::not_found) {
      builtins |= shader::BuiltinBits::POINT_COORD;
    }
    if (source.find("gl_PointSize", 0) != StringRef::not_found) {
      builtins |= shader::BuiltinBits::POINT_SIZE;
    }
    if (source.find("gl_PrimitiveID", 0) != StringRef::not_found) {
      builtins |= shader::BuiltinBits::PRIMITIVE_ID;
    }
    if (source.find("gl_VertexID", 0) != StringRef::not_found) {
      builtins |= shader::BuiltinBits::VERTEX_ID;
    }
    if (source.find("gl_WorkGroupID", 0) != StringRef::not_found) {
      builtins |= shader::BuiltinBits::WORK_GROUP_ID;
    }
    if (source.find("gl_WorkGroupSize", 0) != StringRef::not_found) {
      builtins |= shader::BuiltinBits::WORK_GROUP_SIZE;
    }
    /* TODO(fclem): We could do that at compile time. */
    /* Limit to shared header files to avoid the temptation to use C++ syntax in .glsl files. */
    if (filename.endswith(".h") || filename.endswith(".hh")) {
      enum_preprocess();
      quote_preprocess();
    }
    else {
      if (source.find("'") != StringRef::not_found) {
        char_literals_preprocess();
      }
      if (source.find("drw_print") != StringRef::not_found) {
        string_preprocess();
      }
      if ((source.find("drw_debug_") != StringRef::not_found) &&
          /* Avoid these two files where it makes no sense to add the dependency. */
          !ELEM(filename, "common_debug_draw_lib.glsl", "draw_debug_draw_display_vert.glsl")) {
        builtins |= shader::BuiltinBits::USE_DEBUG_DRAW;
      }
      check_no_quotes();
    }

    if (is_from_material_library()) {
      material_functions_parse(g_functions);
    }
  };

  static bool is_in_comment(const StringRef &input, int64_t offset)
  {
    return (input.rfind("/*", offset) > input.rfind("*/", offset)) ||
           (input.rfind("//", offset) > input.rfind("\n", offset));
  }

  template<bool check_whole_word = true, bool reversed = false, typename T>
  static int64_t find_str(const StringRef &input, const T keyword, int64_t offset = 0)
  {
    while (true) {
      if constexpr (reversed) {
        offset = input.rfind(keyword, offset);
      }
      else {
        offset = input.find(keyword, offset);
      }
      if (offset > 0) {
        if constexpr (check_whole_word) {
          /* Fix false positive if something has "enum" as suffix. */
          char previous_char = input[offset - 1];
          if (!ELEM(previous_char, '\n', '\t', ' ', ':', '(', ',')) {
            offset += (reversed) ? -1 : 1;
            continue;
          }
        }
        /* Fix case where the keyword is in a comment. */
        if (is_in_comment(input, offset)) {
          offset += (reversed) ? -1 : 1;
          continue;
        }
      }
      return offset;
    }
  }

#define find_keyword find_str<true, false>
#define rfind_keyword find_str<true, true>
#define find_token find_str<false, false>
#define rfind_token find_str<false, true>

  void print_error(const StringRef &input, int64_t offset, const StringRef message)
  {
    StringRef sub = input.substr(0, offset);
    int64_t line_number = std::count(sub.begin(), sub.end(), '\n') + 1;
    int64_t line_end = input.find("\n", offset);
    int64_t line_start = input.rfind("\n", offset) + 1;
    int64_t char_number = offset - line_start + 1;

    /* TODO Use clog. */

    std::cout << fullpath << ":" << line_number << ":" << char_number;

    std::cout << " error: " << message << "\n";
    std::cout << std::setw(5) << line_number << " | "
              << input.substr(line_start, line_end - line_start) << "\n";
    std::cout << "      | ";
    for (int64_t i = 0; i < char_number - 1; i++) {
      std::cout << " ";
    }
    std::cout << "^\n";
  }

#define CHECK(test_value, str, ofs, msg) \
  if ((test_value) == -1) { \
    print_error(str, ofs, msg); \
    continue; \
  }

  /**
   * Some drivers completely forbid quote characters even in unused preprocessor directives.
   * We fix the cases where we can't manually patch in `enum_preprocess()`.
   * This check ensure none are present in non-patched sources. (see T97545)
   */
  void check_no_quotes()
  {
#ifdef DEBUG
    int64_t pos = -1;
    do {
      pos = source.find('"', pos + 1);
      if (pos == -1) {
        break;
      }
      if (!is_in_comment(source, pos)) {
        print_error(source, pos, "Quote characters are forbidden in GLSL files");
      }
    } while (true);
#endif
  }

  /**
   * Some drivers completely forbid string characters even in unused preprocessor directives.
   * This fixes the cases we cannot manually patch: Shared headers #includes. (see T97545)
   * TODO(fclem): This could be done during the datatoc step.
   */
  void quote_preprocess()
  {
    if (source.find_first_of('"') == -1) {
      return;
    }

    processed_source = source;
    std::replace(processed_source.begin(), processed_source.end(), '"', ' ');

    source = processed_source.c_str();
  }

  /**
   * Transform C,C++ enum declaration into GLSL compatible defines and constants:
   *
   * \code{.cpp}
   * enum eMyEnum : uint32_t {
   *   ENUM_1 = 0u,
   *   ENUM_2 = 1u,
   *   ENUM_3 = 2u,
   * };
   * \endcode
   *
   * or
   *
   * \code{.c}
   * enum eMyEnum {
   *   ENUM_1 = 0u,
   *   ENUM_2 = 1u,
   *   ENUM_3 = 2u,
   * };
   * \endcode
   *
   * becomes
   *
   * \code{.glsl}
   * #define eMyEnum uint
   * const uint ENUM_1 = 0u, ENUM_2 = 1u, ENUM_3 = 2u;
   * \endcode
   *
   * IMPORTANT: This has some requirements:
   * - Enums needs to have underlying types specified to uint32_t to make them usable in UBO/SSBO.
   * - All values needs to be specified using constant literals to avoid compiler differences.
   * - All values needs to have the 'u' suffix to avoid GLSL compiler errors.
   */
  void enum_preprocess()
  {
    const StringRefNull input = source;
    std::string output;
    int64_t cursor = -1;
    int64_t last_pos = 0;
    const bool is_cpp = filename.endswith(".hh");

    while (true) {
      cursor = find_keyword(input, "enum ", cursor + 1);
      if (cursor == -1) {
        break;
      }
      /* Skip matches like `typedef enum myEnum myType;` */
      if (cursor >= 8 && input.substr(cursor - 8, 8) == "typedef ") {
        continue;
      }
      /* Output anything between 2 enums blocks. */
      output += input.substr(last_pos, cursor - last_pos);

      /* Extract enum type name. */
      int64_t name_start = input.find(" ", cursor);

      int64_t values_start = find_token(input, '{', cursor);
      CHECK(values_start, input, cursor, "Malformed enum class. Expected \'{\' after typename.");

      StringRef enum_name = input.substr(name_start, values_start - name_start);
      if (is_cpp) {
        int64_t name_end = find_token(enum_name, ":");
        CHECK(name_end, input, name_start, "Expected \':\' after C++ enum name.");

        int64_t underlying_type = find_keyword(enum_name, "uint32_t", name_end);
        CHECK(underlying_type, input, name_start, "C++ enums needs uint32_t underlying type.");

        enum_name = input.substr(name_start, name_end);
      }

      output += "#define " + enum_name + " uint\n";

      /* Extract enum values. */
      int64_t values_end = find_token(input, '}', values_start);
      CHECK(values_end, input, cursor, "Malformed enum class. Expected \'}\' after values.");

      /* Skip opening brackets. */
      values_start += 1;

      StringRef enum_values = input.substr(values_start, values_end - values_start);

      /* Really poor check. Could be done better. */
      int64_t token = find_token(enum_values, '{');
      int64_t not_found = (token == -1) ? 0 : -1;
      CHECK(not_found, input, values_start + token, "Unexpected \'{\' token inside enum values.");

      /* Do not capture the comma after the last value (if present). */
      int64_t last_equal = rfind_token(enum_values, '=', values_end);
      int64_t last_comma = rfind_token(enum_values, ',', values_end);
      if (last_comma > last_equal) {
        enum_values = input.substr(values_start, last_comma);
      }

      output += "const uint " + enum_values;

      int64_t semicolon_found = (input[values_end + 1] == ';') ? 0 : -1;
      CHECK(semicolon_found, input, values_end + 1, "Expected \';\' after enum type declaration.");

      /* Skip the curly bracket but not the semicolon. */
      cursor = last_pos = values_end + 1;
    }
    /* If nothing has been changed, do not allocate processed_source. */
    if (last_pos == 0) {
      return;
    }

    if (last_pos != 0) {
      output += input.substr(last_pos);
    }

    processed_source = output;
    source = processed_source.c_str();
  };

  void material_functions_parse(GPUFunctionDictionnary *g_functions)
  {
    const StringRefNull input = source;

    const char whitespace_chars[] = " \r\n\t";

    auto function_parse = [&](const StringRef input,
                              int64_t &cursor,
                              StringRef &out_return_type,
                              StringRef &out_name,
                              StringRef &out_args) -> bool {
      cursor = find_keyword(input, "void ", cursor + 1);
      if (cursor == -1) {
        return false;
      }
      int64_t arg_start = find_token(input, '(', cursor);
      if (arg_start == -1) {
        return false;
      }
      int64_t arg_end = find_token(input, ')', arg_start);
      if (arg_end == -1) {
        return false;
      }
      int64_t body_start = find_token(input, '{', arg_end);
      int64_t next_semicolon = find_token(input, ';', arg_end);
      if (body_start != -1 && next_semicolon != -1 && body_start > next_semicolon) {
        /* Assert no prototypes but could also just skip them. */
        BLI_assert_msg(false, "No prototypes allowed in node GLSL libraries.");
      }
      int64_t name_start = input.find_first_not_of(whitespace_chars, input.find(' ', cursor));
      if (name_start == -1) {
        return false;
      }
      int64_t name_end = input.find_last_not_of(whitespace_chars, arg_start);
      if (name_end == -1) {
        return false;
      }
      /* Only support void type for now. */
      out_return_type = "void";
      out_name = input.substr(name_start, name_end - name_start);
      out_args = input.substr(arg_start + 1, arg_end - (arg_start + 1));
      return true;
    };

    auto keyword_parse = [&](const StringRef str, int64_t &cursor) -> StringRef {
      int64_t keyword_start = str.find_first_not_of(whitespace_chars, cursor);
      if (keyword_start == -1) {
        /* No keyword found. */
        return str.substr(0, 0);
      }
      int64_t keyword_end = str.find_first_of(whitespace_chars, keyword_start);
      if (keyword_end == -1) {
        /* Last keyword. */
        keyword_end = str.size();
      }
      cursor = keyword_end + 1;
      return str.substr(keyword_start, keyword_end - keyword_start);
    };

    auto arg_parse = [&](const StringRef str,
                         int64_t &cursor,
                         StringRef &out_qualifier,
                         StringRef &out_type,
                         StringRef &out_name) -> bool {
      int64_t arg_start = cursor + 1;
      if (arg_start >= str.size()) {
        return false;
      }
      cursor = find_token(str, ',', arg_start);
      if (cursor == -1) {
        /* Last argument. */
        cursor = str.size();
      }
      const StringRef arg = str.substr(arg_start, cursor - arg_start);

      int64_t keyword_cursor = 0;
      out_qualifier = keyword_parse(arg, keyword_cursor);
      out_type = keyword_parse(arg, keyword_cursor);
      out_name = keyword_parse(arg, keyword_cursor);
      if (out_name.is_empty()) {
        /* No qualifier case. */
        out_name = out_type;
        out_type = out_qualifier;
        out_qualifier = arg.substr(0, 0);
      }
      return true;
    };

    int64_t cursor = -1;
    StringRef func_return_type, func_name, func_args;
    while (function_parse(input, cursor, func_return_type, func_name, func_args)) {
      GPUFunction *func = MEM_new<GPUFunction>(__func__);
      func_name.copy(func->name, sizeof(func->name));
      func->source = reinterpret_cast<void *>(this);

      bool insert = g_functions->add(func->name, func);

      /* NOTE: We allow overloading non void function, but only if the function comes from the
       * same file. Otherwise the dependency system breaks. */
      if (!insert) {
        GPUSource *other_source = reinterpret_cast<GPUSource *>(
            g_functions->lookup(func_name)->source);
        if (other_source != this) {
          print_error(input,
                      source.find(func_name),
                      "Function redefinition or overload in two different files ...");
          print_error(
              input, other_source->source.find(func_name), "... previous definition was here");
        }
        else {
          /* Non-void function overload. */
          MEM_delete(func);
        }
        continue;
      }

      if (func_return_type != "void") {
        continue;
      }

      func->totparam = 0;
      int64_t args_cursor = -1;
      StringRef arg_qualifier, arg_type, arg_name;
      while (arg_parse(func_args, args_cursor, arg_qualifier, arg_type, arg_name)) {

        if (func->totparam >= ARRAY_SIZE(func->paramtype)) {
          print_error(input, source.find(func_name), "Too much parameter in function");
          break;
        }

        auto parse_qualifier = [](StringRef qualifier) -> GPUFunctionQual {
          if (qualifier == "out") {
            return FUNCTION_QUAL_OUT;
          }
          if (qualifier == "inout") {
            return FUNCTION_QUAL_INOUT;
          }
          return FUNCTION_QUAL_IN;
        };

        auto parse_type = [](StringRef type) -> eGPUType {
          if (type == "float") {
            return GPU_FLOAT;
          }
          if (type == "vec2") {
            return GPU_VEC2;
          }
          if (type == "vec3") {
            return GPU_VEC3;
          }
          if (type == "vec4") {
            return GPU_VEC4;
          }
          if (type == "mat3") {
            return GPU_MAT3;
          }
          if (type == "mat4") {
            return GPU_MAT4;
          }
          if (type == "sampler1DArray") {
            return GPU_TEX1D_ARRAY;
          }
          if (type == "sampler2DArray") {
            return GPU_TEX2D_ARRAY;
          }
          if (type == "sampler2D") {
            return GPU_TEX2D;
          }
          if (type == "sampler3D") {
            return GPU_TEX3D;
          }
          if (type == "Closure") {
            return GPU_CLOSURE;
          }
          return GPU_NONE;
        };

        func->paramqual[func->totparam] = parse_qualifier(arg_qualifier);
        func->paramtype[func->totparam] = parse_type(arg_type);

        if (func->paramtype[func->totparam] == GPU_NONE) {
          std::string err = "Unknown parameter type \"" + arg_type + "\"";
          int64_t err_ofs = source.find(func_name);
          err_ofs = find_keyword(source, arg_name, err_ofs);
          err_ofs = rfind_keyword(source, arg_type, err_ofs);
          print_error(input, err_ofs, err);
        }

        func->totparam++;
      }
    }
  }

  void char_literals_preprocess()
  {
    const StringRefNull input = source;
    std::stringstream output;
    int64_t cursor = -1;
    int64_t last_pos = 0;

    while (true) {
      cursor = find_token(input, '\'', cursor + 1);
      if (cursor == -1) {
        break;
      }
      /* Output anything between 2 print statement. */
      output << input.substr(last_pos, cursor - last_pos);

      /* Extract string. */
      int64_t char_start = cursor + 1;
      int64_t char_end = find_token(input, '\'', char_start);
      CHECK(char_end, input, cursor, "Malformed char literal. Missing ending `'`.");

      StringRef input_char = input.substr(char_start, char_end - char_start);
      if (input_char.size() == 0) {
        CHECK(-1, input, cursor, "Malformed char literal. Empty character constant");
      }

      uint8_t char_value = input_char[0];

      if (input_char[0] == '\\') {
        if (input_char[1] == 'n') {
          char_value = '\n';
        }
        else {
          CHECK(-1, input, cursor, "Unsupported escaped character");
        }
      }
      else {
        if (input_char.size() > 1) {
          CHECK(-1, input, cursor, "Malformed char literal. Multi-character character constant");
        }
      }

      char hex[8];
      SNPRINTF(hex, "0x%.2Xu", char_value);
      output << hex;

      cursor = last_pos = char_end + 1;
    }
    /* If nothing has been changed, do not allocate processed_source. */
    if (last_pos == 0) {
      return;
    }

    if (last_pos != 0) {
      output << input.substr(last_pos);
    }
    processed_source = output.str();
    source = processed_source.c_str();
  }

  /* Replace print(string) by equivalent drw_print_char4() sequence. */
  void string_preprocess()
  {
    const StringRefNull input = source;
    std::stringstream output;
    int64_t cursor = -1;
    int64_t last_pos = 0;

    while (true) {
      cursor = find_keyword(input, "drw_print", cursor + 1);
      if (cursor == -1) {
        break;
      }

      bool do_endl = false;
      StringRef func = input.substr(cursor);
      if (func.startswith("drw_print(")) {
        do_endl = true;
      }
      else if (func.startswith("drw_print_no_endl(")) {
        do_endl = false;
      }
      else {
        continue;
      }

      /* Output anything between 2 print statement. */
      output << input.substr(last_pos, cursor - last_pos);

      /* Extract string. */
      int64_t str_start = input.find('(', cursor) + 1;
      int64_t semicolon = find_token(input, ';', str_start + 1);
      CHECK(semicolon, input, cursor, "Malformed print(). Missing `;` .");
      int64_t str_end = rfind_token(input, ')', semicolon);
      if (str_end < str_start) {
        CHECK(-1, input, cursor, "Malformed print(). Missing closing `)` .");
      }

      std::stringstream sub_output;
      StringRef input_args = input.substr(str_start, str_end - str_start);

      auto print_string = [&](std::string str) -> int {
        size_t len_before_pad = str.length();
        /* Pad string to uint size. */
        while (str.length() % 4 != 0) {
          str += " ";
        }
        /* Keep everything in one line to not mess with the shader logs. */
        sub_output << "/* " << str << "*/";
        sub_output << "drw_print_string_start(" << len_before_pad << ");";
        for (size_t i = 0; i < len_before_pad; i += 4) {
          uint8_t chars[4] = {*(reinterpret_cast<const uint8_t *>(str.c_str()) + i + 0),
                              *(reinterpret_cast<const uint8_t *>(str.c_str()) + i + 1),
                              *(reinterpret_cast<const uint8_t *>(str.c_str()) + i + 2),
                              *(reinterpret_cast<const uint8_t *>(str.c_str()) + i + 3)};
          if (i + 4 > len_before_pad) {
            chars[len_before_pad - i] = '\0';
          }
          char uint_hex[12];
          SNPRINTF(uint_hex, "0x%.2X%.2X%.2X%.2Xu", chars[3], chars[2], chars[1], chars[0]);
          sub_output << "drw_print_char4(" << StringRefNull(uint_hex) << ");";
        }
        return 0;
      };

      std::string func_args = input_args;
      /* Workaround to support function call inside prints. We replace commas by a non control
       * character `$` in order to use simpler regex later. */
      bool string_scope = false;
      int func_scope = 0;
      for (char &c : func_args) {
        if (c == '"') {
          string_scope = !string_scope;
        }
        else if (!string_scope) {
          if (c == '(') {
            func_scope++;
          }
          else if (c == ')') {
            func_scope--;
          }
          else if (c == ',' && func_scope != 0) {
            c = '$';
          }
        }
      }

      const bool print_as_variable = (input_args[0] != '"') && find_token(input_args, ',') == -1;
      if (print_as_variable) {
        /* Variable or expression debugging. */
        std::string arg = input_args;
        /* Pad align most values. */
        while (arg.length() % 4 != 0) {
          arg += " ";
        }
        print_string(arg);
        print_string("= ");
        sub_output << "drw_print_value(" << input_args << ");";
      }
      else {
        const std::regex arg_regex(
            /* String args. */
            "[\\s]*\"([^\r\n\t\f\v\"]*)\""
            /* OR. */
            "|"
            /* value args. */
            "([^,]+)");
        std::smatch args_match;
        std::string::const_iterator args_search_start(func_args.cbegin());
        while (std::regex_search(args_search_start, func_args.cend(), args_match, arg_regex)) {
          args_search_start = args_match.suffix().first;
          std::string arg_string = args_match[1].str();
          std::string arg_val = args_match[2].str();

          if (arg_string.empty()) {
            for (char &c : arg_val) {
              if (c == '$') {
                c = ',';
              }
            }
            sub_output << "drw_print_value(" << arg_val << ");";
          }
          else {
            print_string(arg_string);
          }
        }
      }

      if (do_endl) {
        sub_output << "drw_print_newline();";
      }

      output << sub_output.str();

      cursor = last_pos = str_end + 1;
    }
    /* If nothing has been changed, do not allocate processed_source. */
    if (last_pos == 0) {
      return;
    }

    if (filename != "common_debug_print_lib.glsl") {
      builtins |= shader::BuiltinBits::USE_DEBUG_PRINT;
    }

    if (last_pos != 0) {
      output << input.substr(last_pos);
    }
    processed_source = output.str();
    source = processed_source.c_str();
  }

#undef find_keyword
#undef rfind_keyword
#undef find_token
#undef rfind_token

  /* Return 1 one error. */
  int init_dependencies(const GPUSourceDictionnary &dict,
                        const GPUFunctionDictionnary &g_functions)
  {
    if (this->dependencies_init) {
      return 0;
    }
    this->dependencies_init = true;
    int64_t pos = -1;

    using namespace shader;
    /* Auto dependency injection for debug capabilities. */
    if ((builtins & BuiltinBits::USE_DEBUG_DRAW) == BuiltinBits::USE_DEBUG_DRAW) {
      dependencies.append_non_duplicates(dict.lookup("common_debug_draw_lib.glsl"));
    }
    if ((builtins & BuiltinBits::USE_DEBUG_PRINT) == BuiltinBits::USE_DEBUG_PRINT) {
      dependencies.append_non_duplicates(dict.lookup("common_debug_print_lib.glsl"));
    }

    while (true) {
      GPUSource *dependency_source = nullptr;

      {
        pos = source.find("pragma BLENDER_REQUIRE(", pos + 1);
        if (pos == -1) {
          return 0;
        }
        int64_t start = source.find('(', pos) + 1;
        int64_t end = source.find(')', pos);
        if (end == -1) {
          print_error(source, start, "Malformed BLENDER_REQUIRE: Missing \")\" token");
          return 1;
        }
        StringRef dependency_name = source.substr(start, end - start);
        dependency_source = dict.lookup_default(dependency_name, nullptr);
        if (dependency_source == nullptr) {
          print_error(source, start, "Dependency not found");
          return 1;
        }
      }

      /* Recursive. */
      int result = dependency_source->init_dependencies(dict, g_functions);
      if (result != 0) {
        return 1;
      }

      for (auto *dep : dependency_source->dependencies) {
        dependencies.append_non_duplicates(dep);
      }
      dependencies.append_non_duplicates(dependency_source);
    }
    return 0;
  }

  /* Returns the final string with all includes done. */
  void build(Vector<const char *> &result) const
  {
    for (auto *dep : dependencies) {
      result.append(dep->source.c_str());
    }
    result.append(source.c_str());
  }

  shader::BuiltinBits builtins_get() const
  {
    shader::BuiltinBits out_builtins = builtins;
    for (auto *dep : dependencies) {
      out_builtins |= dep->builtins;
    }
    return out_builtins;
  }

  bool is_from_material_library() const
  {
    return (filename.startswith("gpu_shader_material_") ||
            filename.startswith("gpu_shader_common_") ||
            filename.startswith("gpu_shader_compositor_")) &&
           filename.endswith(".glsl");
  }
};

}  // namespace blender::gpu

using namespace blender::gpu;

static GPUSourceDictionnary *g_sources = nullptr;
static GPUFunctionDictionnary *g_functions = nullptr;

void gpu_shader_dependency_init()
{
  g_sources = new GPUSourceDictionnary();
  g_functions = new GPUFunctionDictionnary();

#define SHADER_SOURCE(datatoc, filename, filepath) \
  g_sources->add_new(filename, new GPUSource(filepath, filename, datatoc, g_functions));
#include "glsl_compositor_source_list.h"
#include "glsl_draw_source_list.h"
#include "glsl_gpu_source_list.h"
#ifdef WITH_OCIO
#  include "glsl_ocio_source_list.h"
#endif
#undef SHADER_SOURCE

  int errors = 0;
  for (auto *value : g_sources->values()) {
    errors += value->init_dependencies(*g_sources, *g_functions);
  }
  BLI_assert_msg(errors == 0, "Dependency errors detected: Aborting");
  UNUSED_VARS_NDEBUG(errors);
}

void gpu_shader_dependency_exit()
{
  for (auto *value : g_sources->values()) {
    delete value;
  }
  for (auto *value : g_functions->values()) {
    MEM_delete(value);
  }
  delete g_sources;
  delete g_functions;
}

GPUFunction *gpu_material_library_use_function(GSet *used_libraries, const char *name)
{
  GPUFunction *function = g_functions->lookup_default(name, nullptr);
  BLI_assert_msg(function != nullptr, "Requested function not in the function library");
  GPUSource *source = reinterpret_cast<GPUSource *>(function->source);
  BLI_gset_add(used_libraries, const_cast<char *>(source->filename.c_str()));
  return function;
}

namespace blender::gpu::shader {

BuiltinBits gpu_shader_dependency_get_builtins(const StringRefNull shader_source_name)
{
  if (shader_source_name.is_empty()) {
    return shader::BuiltinBits::NONE;
  }
  if (g_sources->contains(shader_source_name) == false) {
    std::cout << "Error: Could not find \"" << shader_source_name
              << "\" in the list of registered source.\n";
    BLI_assert(0);
    return shader::BuiltinBits::NONE;
  }
  GPUSource *source = g_sources->lookup(shader_source_name);
  return source->builtins_get();
}

Vector<const char *> gpu_shader_dependency_get_resolved_source(
    const StringRefNull shader_source_name)
{
  Vector<const char *> result;
  GPUSource *src = g_sources->lookup_default(shader_source_name, nullptr);
  if (src == nullptr) {
    std::cout << "Error source not found : " << shader_source_name << std::endl;
  }
  src->build(result);
  return result;
}

StringRefNull gpu_shader_dependency_get_source(const StringRefNull shader_source_name)
{
  GPUSource *src = g_sources->lookup_default(shader_source_name, nullptr);
  if (src == nullptr) {
    std::cout << "Error source not found : " << shader_source_name << std::endl;
  }
  return src->source;
}

StringRefNull gpu_shader_dependency_get_filename_from_source_string(
    const StringRefNull source_string)
{
  for (auto &source : g_sources->values()) {
    if (source->source.c_str() == source_string.c_str()) {
      return source->filename;
    }
  }
  return "";
}

}  // namespace blender::gpu::shader