layers.js

const commonPoi = {
  "type": "symbol",
  "source-layer": "poi",
  "layout": {
    "icon-image": [
      "coalesce",
      [
        "image",
        [
          "concat",
          [
            "literal",
            "indoorequal-"
          ],
          [
            "get",
            "subclass"
          ]
        ],
      ],
      [
        "image",
        [
          "concat",
          [
            "literal",
            "indoorequal-"
          ],
          [
            "get",
            "class"
          ]
        ]
      ]
    ],
    "text-anchor": "top",
    "text-field": [
      "case",
      // aeroway=gate
      ["==", ["get", "class"], "aeroway"],
      ["get", "ref"],
      // default
      ["concat",
       ["get", "name:latin"],
       "\n",
       ["get", "name:nonlatin"]
      ],
    ],
    "text-max-width": 9,
    "text-offset": [
      0,
      0.6
    ],
    "text-padding": 2,
    "text-size": 12
  },
  "paint": {
    "text-color": "#666",
    "text-halo-blur": 0.5,
    "text-halo-color": "#ffffff",
    "text-halo-width": 1
  }
};

const rank2Class = ["waste_basket", "information", "vending_machine", "bench", "photo_booth", "ticket_validator"];

export const layers = [
  {
    id: "indoor-polygon",
    type: "fill",
    "source-layer": "area",
    filter: [
      "all",
      [
        "==",
        "$type",
        "Polygon"
      ],
      [
        "!=",
        "class",
        "level"
      ]
    ],
    paint: {
      "fill-color": [
        "case",
        // if private
        ["all", ["has", "access"], ["in", ["get", "access"], ["literal", ["no", "private"]]]],
        "#F2F1F0",
        // if POI
        ["any",
         ["all", ["==", ["get", "is_poi"], true], ["!=", ["get", "class"], "corridor"]],
         [
           "in",
           ["get", "subclass"],
           ["literal", ["class", "laboratory", "office", "auditorium", "amphitheatre", "reception"]]]
        ],
        "#D4EDFF",
        // if is a room
        ["==", ["get", "class"], "room"],
        "#fefee2",
        // default
        "#fdfcfa"
      ]
    }
  },
  {
    id: "indoor-area",
    "type": "line",
    "source-layer": "area",
    "filter": [
      "all",
      [
        "in",
        "class",
        "area",
        "corridor",
        "platform"
      ]
    ],
    "paint": {
      "line-color": "#bfbfbf",
      "line-width": 1
    }
  },
  {
    id: "indoor-column",
    "type": "fill",
    "source-layer": "area",
    "filter": [
      "all",
      [
        "==",
        "class",
        "column"
      ]
    ],
    "paint": {
      "fill-color": "#bfbfbf"
    }
  },
  {
    id: "indoor-lines",
    "type": "line",
    "source-layer": "area",
    "filter": [
      "all",
      [
        "in",
        "class",
        "room",
        "wall"
      ]
    ],
    "paint": {
      "line-color": "gray",
      "line-width": 2
    }
  },
  {
    id: "indoor-transportation",
    "type": "line",
    "source-layer": "transportation",
    "filter": [
      "all"
    ],
    "paint": {
      "line-color": "gray",
      "line-dasharray": [
        0.4,
        0.75
      ],
      "line-width": {
        "base": 1.4,
        "stops": [
          [
            17,
            2
          ],
          [
            20,
            10
          ]
        ]
      }
    }
  },
  {
    id: "indoor-transportation-poi",
    "type": "symbol",
    "source-layer": "transportation",
    "filter": [
      "all",
      [
        "in",
        "$type",
        "Point",
        "LineString"
      ],
      [
        "in",
        "class",
        "steps",
        "elevator",
        "escalator"
      ]
    ],
    "layout": {
      "icon-image": [
        "case",
        [
          "has",
          "conveying"
        ],
        "indoorequal-escalator",
        [
          "concat",
          [
            "literal",
            "indoorequal-"
          ],
          [
            "get",
            "class"
          ]
        ]
      ],
      "symbol-placement": "line-center",
      "icon-rotation-alignment": "viewport"
    }
  },
  {
    id: "indoor-poi-rank1",
    ...commonPoi,
    "filter": [
      "all",
      [
        "==",
        "$type",
        "Point"
      ],
      [
        "!in",
        "class",
        ...rank2Class
      ]
    ]
  },
  {
    id: "indoor-poi-rank2",
    ...commonPoi,
    minzoom: 19,
    "filter": [
      "all",
      [
        "==",
        "$type",
        "Point"
      ],
      [
        "in",
        "class",
        ...rank2Class
      ]
    ]
  },
  {
    id: "indoor-heat",
    "type": "heatmap",
    "source-layer": "heat",
    "filter": [ "all" ],
    "paint": {
      "heatmap-color": ["interpolate", ["linear"], ["heatmap-density"],
        0, "rgba(102, 103, 173, 0)",
        0.1, "rgba(102, 103, 173, 0.2)",
        1, "rgba(102, 103, 173, 0.7)"
      ],
      "heatmap-radius": [
        "interpolate", ["linear"], ["zoom"],
        0, 3,
        13, 20,
        17, 40
      ],
      "heatmap-intensity": 1,
      "heatmap-opacity": [
        "interpolate", ["linear"], ["zoom"],
        16, 1,
        17.1, 0
      ]
    }
  },
  {
    id: "indoor-name",
    "type": "symbol",
    "source-layer": "area_name",
    "filter": [
      "all"
    ],
    "layout": {
      "text-field": [
        "concat",
        ["coalesce",
         ["get", "name:latin"],
         ["get", "ref"],
        ],
        "\n",
        ["get", "name:nonlatin"],
      ],
      "text-max-width": 5,
      "text-size": 14
    },
    "paint": {
      "text-color": "#666",
      "text-halo-color": "#ffffff",
      "text-halo-width": 1
    }
  }
];