let
  lib = import <nixpkgs/lib>;
  webConfig = import ../config/web.nix;
  webValidation = import ../validation/web.nix;

  stores = webValidation.getStores webConfig;

  stripPrefix = prefix: value:
    let
      prefixLen = builtins.stringLength prefix;
      valueLen = builtins.stringLength value;
    in
      if valueLen >= prefixLen && builtins.substring 0 prefixLen value == prefix then
        builtins.substring prefixLen (valueLen - prefixLen) value
      else
        value;

  trimLeadingSlash = value:
    if builtins.stringLength value > 0 && builtins.substring 0 1 value == "/" then
      builtins.substring 1 (builtins.stringLength value - 1) value
    else
      value;

  findFiles = dir:
    let
      entries = builtins.readDir dir;
      processEntry = name: type:
        let
          path = dir + "/${name}";
        in
          if type == "directory" then
            findFiles path
          else if type == "regular" then
            [ path ]
          else
            [];
    in
      lib.concatLists (lib.mapAttrsToList processEntry entries);

  detectContentType = relativePath:
    if lib.hasSuffix ".html" relativePath then "text/html"
    else if lib.hasSuffix ".css" relativePath then "text/css"
    else if lib.hasSuffix ".js" relativePath then "application/javascript"
    else if lib.hasSuffix ".json" relativePath then "application/json"
    else if lib.hasSuffix ".svg" relativePath then "image/svg+xml"
    else if lib.hasSuffix ".png" relativePath then "image/png"
    else if lib.hasSuffix ".jpg" relativePath || lib.hasSuffix ".jpeg" relativePath then "image/jpeg"
    else if lib.hasSuffix ".gif" relativePath then "image/gif"
    else if lib.hasSuffix ".webp" relativePath then "image/webp"
    else if lib.hasSuffix ".ico" relativePath then "image/x-icon"
    else if lib.hasSuffix ".txt" relativePath then "text/plain"
    else if lib.hasSuffix ".xml" relativePath then "application/xml"
    else if lib.hasSuffix ".pdf" relativePath then "application/pdf"
    else if lib.hasSuffix ".wasm" relativePath then "application/wasm"
    else "application/octet-stream";

  mkStorePath = storeName: rootPath:
    builtins.path {
      path = rootPath;
      name = "web-store-${storeName}";
    };

  mkStoreFileEntries = storeName: store:
    let
      storeRoot = mkStorePath storeName store.root;
      files = findFiles storeRoot;

      mkFileEntry = filePath:
        let
          filePathString = toString filePath;
          relative = trimLeadingSlash (stripPrefix (toString storeRoot) filePathString);
        in
          {
            path = relative;
            filePath = filePath;
            contentType = detectContentType relative;
            status = 200;
          };

      entries = map mkFileEntry files;
      sortedEntries = builtins.sort (a: b: a.path < b.path) entries;

      paths = map (entry: entry.path) sortedEntries;
      uniquePaths = lib.unique paths;
      _ =
        if builtins.length paths == builtins.length uniquePaths then
          null
        else
          throw "config/web.nix store '${storeName}' produces duplicate relative file paths in root '${toString store.root}'.";
    in
      sortedEntries;

  storeFilesByName = lib.mapAttrs mkStoreFileEntries stores;

  storePayloads = lib.mapAttrs (_: files: {
    type = "store";
    files = files;
  }) storeFilesByName;
in
rec {
  inherit stores storeFilesByName storePayloads;
}