{ config, pkgs, lib, ... }:

with lib;
let
  lspConfig =
    {
      languages = {
        bash = {
          args = [ "start" ];
          command = "bash-language-server";
          filetypes = [ "sh" ];
          roots = [ ".git" ".hg" ];
        };
        c_cpp = {
          args = [ "-v=2" "-log-file=/tmp/ccls.log" ];
          command = "ccls";
          filetypes = [ "c" "cpp" ];
          roots = [ "compile_commands.json" ".cquery" ".git" ];
        };
        crystal = {
          command = "scry";
          filetypes = [ "crystal" ];
          roots = [ "shard.yml" ];
        };
        css = {
          args = [ "--stdio" ];
          command = "css-languageserver";
          filetypes = [ "css" ];
          roots = [ "package.json" ];
        };
        d = {
          command = "dls";
          filetypes = [ "d" "di" ];
          roots = [ ".git" "dub.sdl" "dub.json" ];
        };
        dart = {
          command = "dart_language_server";
          filetypes = [ "dart" ];
          roots = [ "pubspec.yaml" ".git" ];
        };
        elm = {
          args = [ "--stdio" ];
          command = "elm-language-server";
          filetypes = [ "elm" ];
          roots = [ "elm.json" ];
        };
        fsharp = {
          command = "FSharpLanguageServer";
          filetypes = [ "fsharp" ];
          roots = [ ".git" "*.fsx" ];
        };
        go = {
          command = "gopls";
          filetypes = [ "go" ];
          offset_encoding = "utf-8";
          roots = [ "Gopkg.toml" "go.mod" ".git" ".hg" ];
          settings = { gopls = { hoverKind = "SynopsisDocumentation"; semanticTokens = true; }; };
          settings_section = "gopls";
        };
        haskell = {
          args = [ "--lsp" ];
          command = "haskell-language-server-wrapper";
          filetypes = [ "haskell" ];
          roots = [ "Setup.hs" "stack.yaml" "*.cabal" "package.yaml" ];
          settings_section = "haskell";
        };
        html = {
          args = [ "--stdio" ];
          command = "html-languageserver";
          filetypes = [ "html" ];
          roots = [ "package.json" ];
        };
        javascript = {
          args = [ "lsp" ];
          command = "flow";
          filetypes = [ "javascript" ];
          roots = [ ".flowconfig" ];
        };
        json = {
          args = [ "--stdio" ];
          command = "json-languageserver";
          filetypes = [ "json" ];
          roots = [ "package.json" ];
        };
        latex = {
          command = "texlab";
          filetypes = [ "latex" ];
          roots = [ ".git" "main.tex" "all.tex" ];
          settings_section = "texlab";
          settings.texlab = {
            build.executable = "latexmk";
            build.args = [ "-pdf" "-shell-escape" "-interaction=nonstopmode" "-synctex=1" "%f" ];

            build.forwardSearchAfter = true;
            build.onSave = true;

            forwardSearch = {
              executable = "/Applications/Skim.app/Contents/SharedSupport/displayline";
              args = [ "-r" "-g" "%l" "%p" "%f" ];
            };
          };
        };
        nim = {
          command = "nimlsp";
          filetypes = [ "nim" ];
          roots = [ "*.nimble" ".git" ];
        };
        nix = {
          command = "rnix-lsp";
          filetypes = [ "nix" ];
          roots = [ "flake.nix" "shell.nix" ".git" ];
        };
        ocaml = {
          args = [ ];
          command = "ocamllsp";
          filetypes = [ "ocaml" ];
          roots = [ "Makefile" "opam" "*.opam" "dune" ".merlin" ".ocamlformat" ];
        };
        php = {
          args = [ "--stdio" ];
          command = "intelephense";
          filetypes = [ "php" ];
          roots = [ ".htaccess" "composer.json" ];
        };
        python = {
          command = "pyls";
          filetypes = [ "python" ];
          offset_encoding = "utf-8";
          roots = [ "requirements.txt" "setup.py" ".git" ".hg" ];
        };
        racket = {
          args = [ "-l" "racket-langserver" ];
          command = "racket";
          filetypes = [ "racket" ];
          roots = [ ".git" ];
        };
        reason = {
          args = [ "--stdio" ];
          command = "ocaml-language-server";
          filetypes = [ "reason" ];
          roots = [ "package.json" "Makefile" ".git" ".hg" ];
        };
        ruby = {
          args = [ "stdio" ];
          command = "solargraph";
          filetypes = [ "ruby" ];
          roots = [ "Gemfile" ];
        };
        rust = {
          args = [ ];
          command = "rust-analyzer";
          filetypes = [ "rust" ];
          roots = [ "Cargo.toml" ];
        };
      };
      semantic_tokens.faces = [
        ## Items
        # (Rust) Macros
        { face = "attribute"; token = "attribute"; }
        { face = "attribute"; token = "derive"; }
        { face = "macro"; token = "macro"; } # Function-like Macro
        # Keyword and Fixed Tokens
        { face = "keyword"; token = "keyword"; }
        { face = "operator"; token = "operator"; }
        # Functions and Methods
        { face = "function"; token = "function"; }
        { face = "method"; token = "method"; }
        # Constants
        { face = "string"; token = "string"; }
        { face = "format_specifier"; token = "formatSpecifier"; }
        # Variables
        { face = "variable"; token = "variable"; modifiers = [ "readonly" ]; }
        { face = "mutable_variable"; token = "variable"; }
        { face = "module"; token = "namespace"; }
        { face = "variable"; token = "type_parameter"; }
        { face = "class"; token = "enum"; }
        { face = "class"; token = "struct"; }
        { face = "class"; token = "trait"; }
        { face = "class"; token = "union"; }
        { face = "class"; token = "class"; }

        ## Comments
        { face = "documentation"; token = "comment"; modifiers = [ "documentation" ]; }
        { face = "comment"; token = "comment"; }
      ];
      server = { timeout = 1800; };
      snippet_support = false;
      verbosity = 255;
    };

  languageOption = types.submodule {
    options = {
      filetypes = mkOption {
        type = types.listOf types.str;
        description = "The list of filetypes to assign the language to";
      };
      roots = mkOption {
        type = types.listOf types.str;
        description = "The list of root filenames that are used to determine the project root";
      };
      command = mkOption {
        type = types.str;
        description = "The LSP server command to be called.";
      };
      args = mkOption {
        type = types.listOf types.str;
        default = [ ];
        description = "The arguments passed onto the LSP server.";
      };
      offset_encoding = mkOption {
        type = types.nullOr (types.enum [ "utf-8" ]);
        default = null;
        description = "The offset encoding used by the LSP server.";
      };
      settings_section = mkOption {
        type = types.nullOr types.str;
        default = null;
        description = "The settings section to be sent to LSP server.";
      };
      settings = mkOption {
        type = types.nullOr (types.attrsOf types.anything);
        default = null;
        description = "Additional settings to be passed to the LSP server.";
      };
    };
  };

  cfg = config.programs.kak-lsp;
in
{
  options.programs.kak-lsp = {
    enable = mkEnableOption "Enable kak-lsp support";

    package = mkOption {
      type = types.package;
      default = pkgs.kak-lsp;
    };

    enableSnippets = mkOption {
      type = types.bool;
      default = false;
      description = "Enable snippet support";
    };

    semanticTokens.faces = mkOption {
      type = types.listOf types.anything;
      default = lspConfig.semantic_tokens.faces;
      description = "The semantic tokens faces mapping given to kak";
    };
    semanticTokens.additionalFaces = mkOption {
      type = types.listOf types.anything;
      default = [ ];
      description = "The semantic tokens faces mapping given to kak";
    };

    serverTimeout = mkOption {
      type = types.int;
      default = 1000;
      description = "Server timeout";
    };

    languages = mkOption {
      type = types.attrsOf languageOption;
      default = { };
      description = "The language options";
    };
  };

  config = mkIf cfg.enable {
    home.packages = [ cfg.package ];

    # Configurations
    xdg.configFile."kak-lsp/kak-lsp.toml" = {
      source = pkgs.runCommand "config.toml"
        {
          buildInputs = [ pkgs.yj ];
          preferLocalBuild = true;
        } ''
        yj -jt -i \
          < ${
            pkgs.writeText "config.json" (builtins.toJSON {
              semantic_tokens.faces = cfg.semanticTokens.faces ++ cfg.semanticTokens.additionalFaces;
              server.timeout = cfg.serverTimeout;
              snippet_support = cfg.enableSnippets;
              verbosity = 255;
              language = lspConfig.languages // cfg.languages;
            })
          } \
          > $out
      '';
    };
  };
}