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

with lib;

let
  cfg = config.programs.kodi;

  stylesheetCommonHeader = ''
    <?xml version="1.0"?>
    <xsl:stylesheet xmlns:xsl='http://www.w3.org/1999/XSL/Transform' version='1.0'>
    <xsl:output method="xml" indent="yes" omit-xml-declaration="yes"/>
    <xsl:strip-space elements="*"/>
  '';

  stylesheetCommonFooter = "</xsl:stylesheet>";

  stylesheetNestedTags = ''
    <xsl:template match="attr[attrs]">
      <xsl:variable name="elementName" select="@name"/>
      <xsl:element name="{$elementName}">
        <xsl:apply-templates select="attrs" />
      </xsl:element>
    </xsl:template>
    <xsl:template match="attr[list[attrs]]">
    <xsl:variable name="elementName" select="@name"/>
    <xsl:for-each select="list/attrs">
      <xsl:element name="{$elementName}">
        <xsl:apply-templates select="." />
      </xsl:element>
    </xsl:for-each>
    </xsl:template>
    <xsl:template match="attr[not(attrs|list)]">
      <xsl:variable name="elementName" select="@name"/>
      <xsl:element name="{$elementName}">
      <xsl:if test="$elementName='path'">
        <!-- needed in sources.xml but will be used for all "path" tags -->
        <xsl:attribute name="pathversion">1</xsl:attribute>
      </xsl:if>
        <xsl:value-of select="*/@value" />
      </xsl:element>
    </xsl:template>
  '';

  stylesheetTagsAsSettingWithId = ''
    <xsl:template match='attr'>
      <setting>
        <xsl:attribute name="id">
          <xsl:value-of select="@name" />
        </xsl:attribute>
        <xsl:value-of select="*/@value" />
      </setting>
    </xsl:template>
  '';

  stylesheetAdvancedSettingsRootTag = ''
    <xsl:template match='/'>
      <xsl:comment> Generated by Home Manager. </xsl:comment>
      <advancedsettings version="1.0">
        <xsl:apply-templates/>
      </advancedsettings>
    </xsl:template>
  '';

  stylesheetSourcesRootTag = ''
    <xsl:template match='/'>
      <xsl:comment> Generated by Home Manager. </xsl:comment>
      <sources>
        <xsl:apply-templates/>
      </sources>
    </xsl:template>
  '';

  stylesheetAddonSettingsRootTag = ''
    <xsl:template match='/'>
      <xsl:comment> Generated by Home Manager. </xsl:comment>
      <settings version="2">
        <xsl:apply-templates/>
      </settings>
    </xsl:template>
  '';

  attrsetToXml = attrs: name: stylesheet:
    pkgs.runCommand name {
      # Package splicing for libxslt does not work correctly leading to errors
      # when cross-compiling. Use the version from buildPackages explicitly to
      # fix this.
      nativeBuildInputs = [ pkgs.buildPackages.libxslt.bin ];
      xml = builtins.toXML attrs;
      passAsFile = [ "xml" ];
    } ''
      xsltproc ${stylesheet} - < "$xmlPath" > "$out"
    '';

  attrsetToAdvancedSettingsXml = attrs: name:
    let
      stylesheet = builtins.toFile "stylesheet.xsl" ''
        ${stylesheetCommonHeader}
        ${stylesheetAdvancedSettingsRootTag}
        ${stylesheetNestedTags}
        ${stylesheetCommonFooter}
      '';
    in attrsetToXml attrs name stylesheet;

  attrsetToSourcesXml = attrs: name:
    let
      stylesheet = builtins.toFile "stylesheet.xsl" ''
        ${stylesheetCommonHeader}
        ${stylesheetSourcesRootTag}
        ${stylesheetNestedTags}
        ${stylesheetCommonFooter}
      '';
    in attrsetToXml attrs name stylesheet;

  attrsetToAddonSettingsXml = attrs: name:
    let
      stylesheet = builtins.toFile "stylesheet.xsl" ''
        ${stylesheetCommonHeader}
        ${stylesheetAddonSettingsRootTag}
        ${stylesheetTagsAsSettingWithId}
        ${stylesheetCommonFooter}
      '';
    in attrsetToXml attrs name stylesheet;

in {
  meta.maintainers = [ hm.maintainers.dwagenk ];

  options.programs.kodi = {
    enable = mkEnableOption "Kodi";

    package = mkOption {
      type = types.package;
      default = pkgs.kodi;
      defaultText = literalExpression "pkgs.kodi";
      example = literalExpression
        "pkgs.kodi.withPackages (exts: [ exts.pvr-iptvsimple ])";
      description = ''
        The `kodi` package to use.
        Can be used to specify extensions.
      '';
    };

    datadir = mkOption {
      type = types.path;
      default = "${config.home.homeDirectory}/.kodi";
      defaultText =
        literalExpression ''"''${config.home.homeDirectory}/.kodi"'';
      example = literalExpression ''"''${config.xdg.dataHome}/kodi"'';
      description = "Directory to store configuration and metadata.";
    };

    settings = mkOption {
      type = with types;
        let
          valueType = either str (attrsOf valueType) // {
            description = "attribute sets of strings";
          };
        in nullOr valueType;
      default = null;
      example = literalExpression ''
        { videolibrary.showemptytvshows = "true"; }
      '';
      description = ''
        Configuration to write to the `advancedsettings.xml`
        file in kodis userdata directory. Settings specified here will be
        immutable from inside kodi and be hidden from the GUI settings dialog.

        See <https://kodi.wiki/view/Advancedsettings.xml> as
        reference for how settings need to be specified.

        The innermost attributes must be of type str.
      '';
    };

    sources = mkOption {
      type = with types;
        let
          valueType = oneOf [ str (attrsOf valueType) (listOf valueType) ] // {
            description = "attribute sets or lists of strings";
          };
        in nullOr valueType;
      default = null;
      example = literalExpression ''
        {
          video = {
            default = "movies";
            source = [
              { name = "videos"; path = "/path/to/videos"; allowsharing = "true"; }
              { name = "movies"; path = "/path/to/movies"; allowsharing = "true"; }
            ];
          };
        }
      '';
      description = ''
        Contents to populate the file `sources.xml` in kodis
        userdata directory.

        See <https://kodi.wiki/view/Sources.xml> as
        reference for how sources need to be specified.

        Kodi will still show the dialogs to modify sources in the GUI and they
        appear to be mutable. This however is not the case and the sources will
        stay as specified via Home Manager.

        The innermost attributes must be of type str.
      '';
    };

    addonSettings = mkOption {
      type = with types; nullOr (attrsOf (attrsOf str));
      default = null;
      example = literalExpression ''
        { "service.xbmc.versioncheck".versioncheck_enable = "false"; }
      '';
      description = ''
        Attribute set with the plugin namespace as toplevel key and the plugins
        settings as lower level key/value pairs.

        Kodi will still show the settings of plugins configured via this
        mechanism in the GUI and they appear to be mutable. This however is
        not the case and the settings will stay as specified via Home Manager.
      '';
    };
  };

  config = mkIf cfg.enable (mkMerge [
    {
      assertions = [
        (lib.hm.assertions.assertPlatform "programs.kodi" pkgs
          lib.platforms.linux)
      ];

      home.packages = [ cfg.package ];
      home.sessionVariables = { KODI_DATA = cfg.datadir; };
    }

    (mkIf (cfg.settings != null) {
      home.file."${cfg.datadir}/userdata/advancedsettings.xml".source =
        attrsetToAdvancedSettingsXml cfg.settings "kodi-advancedsettings.xml";
    })

    (mkIf (cfg.sources != null) {
      home.file."${cfg.datadir}/userdata/sources.xml".source =
        attrsetToSourcesXml cfg.sources "kodi-sources.xml";
    })

    (mkIf (cfg.addonSettings != null) {
      home.file = mapAttrs' (k: v:
        attrsets.nameValuePair
        ("${cfg.datadir}/userdata/addon_data/${k}/settings.xml") {
          source = attrsetToAddonSettingsXml v "kodi-addon-${k}-settings.xml";
        }) cfg.addonSettings;
    })
  ]);
}