File Coverage

=head1 NAME

HTML::OSM - Generate an interactive OpenStreetMap with Leaflet.js

=head1 VERSION

Version 0.10

=cut

=head1 SYNOPSIS

    use HTML::OSM;

    my $map = HTML::OSM->new(
        coordinates => [
            [37.7749, -122.4194, 'San Francisco'],
            [undef,   undef,     'Paris'],
        ],
        zoom => 10,
    );
    my ($head, $body) = $map->onload_render();

=over 4

=item * Caching

Geocode results are cached via L<CHI> (default: in-memory, 1-day TTL).
Supply your own C<cache> object to persist across processes.

=item * Rate-Limiting

Set C<min_interval> (seconds) to throttle outbound Nominatim calls
and comply with the API fair-use policy.

=back

=head1 SUBROUTINES/METHODS

=head2 new

Construct a new C<HTML::OSM> object.

    my $map = HTML::OSM->new(%params);
    my $map = HTML::OSM->new(\%params);

Both method-style (C<< HTML::OSM->new(...) >>) and function-style
(C<HTML::OSM::new(...)>) calls are supported.
Calling C<< $existing_obj->new(%overrides) >> performs a shallow clone,
merging C<%overrides> onto the existing object's state without re-validating.

=head3 API SPECIFICATION

=head4 INPUT

  {
    cache                   => { type => object, can => [get, set], optional },
    cluster                 => { type => boolean,                   optional },
    cluster_css_url         => { type => string,                    optional },
    cluster_default_css_url => { type => string,                    optional },
    cluster_js_url          => { type => string,                    optional },
    config_file             => { type => string,                    optional },
    coordinates             => { type => arrayref,                  optional },
    css_url                 => { type => string,                    optional },
    geocoder                => { type => object, can => geocode,    optional },
    gpx_js_url              => { type => string,                    optional },
    heatmap_js_url          => { type => string,                    optional },
    height                  => { type => string,                    optional },
    host                    => { type => string,                    optional },
    js_url                  => { type => string,                    optional },
    logger                  => { type => object,                    optional },
    min_interval            => { type => number,  min => 0,         optional },
    ua                      => { type => object,                    optional },
    width                   => { type => string,                    optional },
    zoom                    => { type => integer, min => 0, max => 19, optional },
  }

=head4 OUTPUT

  { type => object, isa => 'HTML::OSM' }

=head3 MESSAGES

  | Message                                        | Meaning / Resolution                          |
  |------------------------------------------------|-----------------------------------------------|
  | (validation error from Params::Validate::Strict) | A param has the wrong type or is out of range |

=head3 PSEUDOCODE

  1. If $class is neither a package name nor a blessed ref, treat as
     function-style call: prepend $class back onto @_ and use __PACKAGE__.
  2. If $class is a blessed ref (clone call): merge override params onto a
     shallow copy and return immediately, bypassing schema validation.
  3. Validate all supplied args against the declared schema.
  4. Merge config-file settings via Object::Configure.
  5. Resolve the cache: caller-supplied object, or in-memory CHI instance.
  6. Bless and return with Readonly CDN constants as defaults.

=cut

=head2 add_marker

Add a point marker to the map.

    $map->add_marker([51.5074, -0.1278], html => 'London');
    $map->add_marker('Paris, France',    html => 'Paris');
    $map->add_marker($geo_coder_result);

Returns 1 on success, 0 if the point cannot be resolved or is out of range.

=head3 API SPECIFICATION

=head4 INPUT

  point : arrayref [lat, lon] | string address | object with latitude()/longitude()
  html  : string   (optional popup label)
  icon  : string   (optional icon URL)

=head4 OUTPUT

  { type => integer, enum => [0, 1] }

=head3 MESSAGES

  | Message                              | Meaning / Resolution                        |
  |--------------------------------------|---------------------------------------------|
  | add_marker(): unknown point type     | Point is a ref type with no lat/lon methods |

=head3 EXAMPLES

    # Coordinate array with a popup label
    $map->add_marker([51.5074, -0.1278], html => 'London');

    # String address geocoded via the injected geocoder or Nominatim
    $map->add_marker('Paris, France', html => 'Paris');

    # Custom icon URL with a popup
    $map->add_marker(
        [40.7128, -74.0060],
        html => 'New York',
        icon => 'https://example.com/pin.png',
    );

    # Geo::Coder result object that implements latitude()/longitude()
    my $result = $geocoder->geocode('Berlin, Germany');
    $map->add_marker($result, html => 'Berlin');

    # Accumulate several markers, warn on geocode failure
    for my $city (@cities) {
        $map->add_marker($city->{coords}, html => $city->{name})
            or warn "Could not place $city->{name}";
    }

=cut

=head2 add_geojson

Add a GeoJSON layer to the map.

    $map->add_geojson(\%data, style => { color => '#ff0000' }, popup => 'name');

The first argument may be a hashref/arrayref (GeoJSON structure) or a JSON string.
Returns 1 on success.

=head3 API SPECIFICATION

=head4 INPUT

  data  : hashref | arrayref | string (JSON)
  style : hashref   Leaflet path-style options (color, weight, fillColor, fillOpacity)
  popup : string    Feature property name whose value becomes the popup text

=head4 OUTPUT

  { type => integer, value => 1 }

=head3 MESSAGES

  | Message              | Meaning / Resolution            |
  |----------------------|---------------------------------|
  | (JSON parse error)   | data string is not valid JSON   |

=head3 EXAMPLES

    # Pre-parsed GeoJSON structure with style and popup property
    $map->add_geojson(
        { type => 'FeatureCollection', features => \@features },
        style => { color => '#ff0000', weight => 2, fillOpacity => 0.4 },
        popup => 'name',
    );

    # Raw JSON string — decoded automatically
    $map->add_geojson('{"type":"FeatureCollection","features":[]}');

    # Multiple GeoJSON layers with different styles on the same map
    $map->add_geojson(\%country_borders, style => { color => '#333333', fillOpacity => 0 });
    $map->add_geojson(\%river_data,      style => { color => '#0099ff', weight => 1    });

=cut

=head2 add_heatmap

Add a heatmap layer to the map.

    $map->add_heatmap([[51.5, -0.1, 0.8], [51.6, -0.2, 0.5]], radius => 25);

Each point is C<[$lat, $lon]> or C<[$lat, $lon, $intensity]> (intensity: 0-1).
Requires the Leaflet.heat plugin (C<heatmap_js_url>).
Returns 1 on success.

=head3 API SPECIFICATION

=head4 INPUT

  points : arrayref of ([lat, lon] | [lat, lon, intensity])
  radius : integer  default 25
  blur   : integer  default 15

=head4 OUTPUT

  { type => integer, value => 1 }

=head3 MESSAGES

  | Message                              | Meaning / Resolution              |
  |--------------------------------------|-----------------------------------|
  | add_heatmap: points must be arrayref | First argument is not an arrayref |

=head3 EXAMPLES

    # Basic heatmap — [lat, lon] per point
    $map->add_heatmap([
        [51.5074, -0.1278],
        [51.6000, -0.2000],
        [51.4000,  0.0000],
    ]);

    # With intensity values (0..1) and custom radius/blur
    $map->add_heatmap(
        [ [51.5, -0.1, 0.9], [51.6, -0.2, 0.5], [51.4, 0.0, 0.2] ],
        radius => 30,
        blur   => 20,
    );

=cut

=head2 add_gpx

Add a GPX track to the map from a URL.

    $map->add_gpx('https://example.com/track.gpx');

The map view is auto-fitted to the track bounds after loading.
Requires the leaflet-gpx plugin (C<gpx_js_url>).
Returns 1 on success.

=head3 API SPECIFICATION

=head4 INPUT

  url : string  URL of the GPX file (required)

=head4 OUTPUT

  { type => integer, value => 1 }

=head3 MESSAGES

  | Message              | Meaning / Resolution       |
  |----------------------|----------------------------|
  | add_gpx: url required | No URL argument supplied  |

=head3 EXAMPLES

    # Add a GPX track from a public URL; the map auto-fits to its bounds
    $map->add_gpx('https://example.com/route.gpx');

    # Multiple tracks on the same map
    $map->add_gpx('https://example.com/morning-run.gpx');
    $map->add_gpx('https://example.com/evening-walk.gpx');

=cut

=head2 add_choropleth

Add a choropleth (data-driven colour fill) layer to the map.

    $map->add_choropleth(
        \@geojson_features,
        { England => 100, Scotland => 80, Wales => 60 },
        key   => 'name',
        scale => ['#ffffcc', '#a1dab4', '#41b6c4', '#2c7fb8', '#253494'],
    );

Colours are pre-computed in Perl and baked into the emitted JavaScript.
No extra browser plugin is required.
Returns 1 on success.

=head3 API SPECIFICATION

=head4 INPUT

  features : arrayref of GeoJSON Feature hashrefs  (required)
  values   : hashref  { feature_property_value => numeric_value }  (required)
  key      : string   feature property to match against values  (default: 'name')
  scale    : arrayref hex-colour strings low-to-high  (default: 5-step YlGnBu)

=head4 OUTPUT

  { type => integer, value => 1 }

=head3 MESSAGES

  | Message                                  | Meaning / Resolution                   |
  |------------------------------------------|----------------------------------------|
  | add_choropleth: features must be arrayref | First argument is not an arrayref      |
  | add_choropleth: values must be hashref    | Second argument is not a hashref       |

=head3 EXAMPLES

    # Default 5-step YlGnBu scale, key property "name"
    $map->add_choropleth(
        \@geojson_features,
        { England => 100, Scotland => 80, Wales => 60 },
    );

    # Custom 3-step scale and a different GeoJSON property as the key
    $map->add_choropleth(
        \@geojson_features,
        { England => 100, Scotland => 80, Wales => 60 },
        key   => 'country',
        scale => ['#f7fbff', '#6baed6', '#08519c'],
    );

    # choropleth-only map — center() must be called explicitly
    $map->center([54.0, -2.0]);
    $map->add_choropleth(\@uk_features, \%population_by_region);
    my ($head, $body) = $map->onload_render();

=cut

=head2 center

Set the map centre to a given point.

    $map->center([40.7128, -74.0060]);
    $map->center($geo_object);
    $map->center('Berlin, Germany');

Returns 1 on success, 0 if the point cannot be resolved.

=head3 API SPECIFICATION

=head4 INPUT

  point : arrayref [lat, lon] | object with latitude()/longitude() | string address

=head4 OUTPUT

  { type => integer, enum => [0, 1] }

=head3 MESSAGES

  | Message                                        | Meaning / Resolution                     |
  |------------------------------------------------|------------------------------------------|
  | center(): usage: point => [lat, lon]           | No point argument supplied               |
  | center(): point must have latitude & longitude | Arrayref has != 2 elements               |
  | center(): unknown point type                   | Ref type has no lat/lon methods          |

=head3 EXAMPLES

    # Coordinate array
    $map->center([40.7128, -74.0060]);

    # Object that implements latitude()/longitude() (e.g. a Geo::Coder result)
    $map->center($geocoder->geocode('Berlin, Germany'));

    # String address resolved via the injected geocoder or Nominatim
    $map->center('Eiffel Tower, Paris, France');

    # Required when rendering without point markers (GeoJSON-only, choropleth, etc.)
    $map->center([54.0, -2.0]);
    $map->add_geojson(\%uk_regions, popup => 'name');
    my ($head, $body) = $map->onload_render();

=cut

=head2 zoom

Get or set the zoom level (0 = world, 19 = building).

    $map->zoom(10);
    my $z = $map->zoom();

=head3 API SPECIFICATION

=head4 INPUT

  { zoom => { type => integer, min => 0, max => 19, optional => 1 } }

=head4 OUTPUT

  { type => integer, min => 0, max => 19 }

=head3 MESSAGES

  | Message                      | Meaning / Resolution                      |
  |------------------------------|-------------------------------------------|
  | (Params::Validate::Strict)   | zoom is not an integer or is out of range |

=head3 EXAMPLES

    # Setter: store the zoom level
    $map->zoom(14);

    # Getter: retrieve the current level
    my $level = $map->zoom();
    print "Current zoom: $level\n";    # 14

    # Setter return value equals the new level
    my $confirmed = $map->zoom(10);
    die 'unexpected' unless $confirmed == 10;

    # Chain: set via new(), read back via zoom()
    my $m = HTML::OSM->new(zoom => 6);
    $m->zoom($m->zoom() + 2);   # nudge up by 2

=cut

=head2 onload_render

Render the map and return a two-element list suitable for embedding in HTML.

    my ($head_html, $body_html) = $map->onload_render();

C<$head_html> contains the Leaflet CSS, JavaScript, and plugin assets.
Place it inside C<< <head>...</head> >>.

C<$body_html> contains the search box, control buttons, map C<< <div> >>,
and the initialisation C<< <script> >>.
Place it inside C<< <body>...</body> >> where the map should appear.

The rendered page provides:

=over 4

=item * A Nominatim-powered search box that adds temporary markers.

=item * A "Clear search markers" button that removes those temporary markers,
leaving static markers (added via C<add_marker>) intact.

=item * A "Reset Map" button that returns the view to the initial centre and zoom.

=back

=head3 API SPECIFICATION

=head4 INPUT

  (none - uses object state)

=head4 OUTPUT

  { type => list, elements => [string, string] }

=head3 MESSAGES

  | Message                                          | Meaning / Resolution                        |
  |--------------------------------------------------|---------------------------------------------|
  | No map data provided                             | No markers, GeoJSON, heatmap, GPX, or choropleth added yet |
  | center() must be called when no point markers    | Non-marker-only render needs explicit centre |

=head3 EXAMPLES

    # Minimal: one marker, embed in a CGI response
    use HTML::OSM;
    my $map = HTML::OSM->new(zoom => 12);
    $map->add_marker([51.5074, -0.1278], html => 'London');
    my ($head, $body) = $map->onload_render();
    print "Content-Type: text/html\n\n";
    print "<html><head>$head</head><body>$body</body></html>\n";

    # Mixed layers: markers + GeoJSON, explicit center
    $map->center([51.5, -0.1]);
    $map->add_geojson(\%borough_data, popup => 'name', style => { color => '#333' });
    $map->add_marker([51.5074, -0.1278], html => 'City of London');
    my ($head_html, $body_html) = $map->onload_render();

    # Template Toolkit integration
    $tt->process('map.tt', {
        map_head => scalar(($map->onload_render())[0]),
        map_body => scalar(($map->onload_render())[1]),
    });

=head3 PSEUDOCODE

  1. Gather all data layers; croak if none populated.
  2. Geocode/validate each coordinate tuple; discard invalids with a warning.
  3. Determine map centre: caller-supplied > computed midpoint of marker bounds.
     Croak if neither is available.
  4. Build <head>: Leaflet CSS + JS; inject cluster/heatmap/GPX plugin assets
     only when the corresponding layer type is present.
  5. Build <body>: search box, clear-search button, reset button, map <div>.
  6. Initialise Leaflet map, tile layer, searchMarkers array.
  7. Emit JS for each marker (via clusterGroup when cluster is set).
  8. Emit JS for each GeoJSON, heatmap, GPX, and choropleth layer.
  9. Attach event listeners: reset-view, clear-search-markers, search-on-Enter.
  10. Return ($head, $body).

=cut

=head1 LIMITATIONS

=over 4

=item * B<Per-marker removal>: Markers added via C<add_marker()> cannot yet be
removed individually by clicking them.  The "Clear search markers" button only
removes markers added by the in-page Nominatim search box.

=item * B<Clone validation>: The clone path (C<< $obj->new(%overrides) >>)
bypasses the Params::Validate::Strict schema so subclasses and internal callers
can merge arbitrary state.  Callers are responsible for passing valid overrides.

=item * B<Config-file params unvalidated>: Keys injected by
L<Object::Configure> from a config file are not re-run through the schema, so
a malformed config file can introduce invalid types at runtime.

=item * B<Private-method encapsulation>: C<_fetch_coordinates>, C<_validate>,
and C<_js_string> are named with a leading underscore by convention only.
Using L<Sub::Private> in C<enforce> mode would make the contract explicit, but
that module is not yet listed as a dependency to avoid breaking white-box tests
in C<t/mock.t>.

=item * B<Routing>: Turn-by-turn routing (Leaflet Routing Machine / OSRM) is
explicitly out of scope for this module and will not be added here.

=back

=head1 AUTHOR

Nigel Horne, C<< <njh at nigelhorne.com> >>

=head1 BUGS

Please report bugs at L<https://github.com/nigelhorne/HTML-OSM/issues>.

=head1 SEE ALSO

=over 4

=item * L<https://wiki.openstreetmap.org/wiki/API>

=item * L<HTML::GoogleMaps::V3> - the interface this module mirrors for compatibility.

=item * L<https://leafletjs.com/>

=item * L<Configure an Object at Runtime|Object::Configure>

=item * L<Test Dashboard|https://nigelhorne.github.io/HTML-OSM/coverage/>

=back

=head1 SUPPORT

This module is provided as-is without any warranty.

L<https://rt.cpan.org/NoAuth/Bugs.html?Dist=HTML-OSM>

=head2 TODO

Allow per-marker removal via clicking on a marker.

=encoding utf-8

=head1 FORMAL SPECIFICATION

=head2 new

  HTML_OSM
    coordinates     : iseq (ℝ x ℝ x S x S)
    zoom            : Z
    cluster         : B
  ----------------------------------------
    ZOOM_MIN <= zoom <= ZOOM_MAX

  new ≙
    params? : Params
    osm!    : HTML_OSM
  ----------------------------------------
    osm!.zoom     = params?.zoom     âˆ¨ 12
    osm!.cluster  = params?.cluster  âˆ¨ false

=head2 add_marker

  AddMarker
    Î”HTML_OSM
    point? : (ℝ x ℝ) ∪ S ∪ GeoObject
    result! : {0, 1}
  -----------------------------------------
    result! = 1 ⟺ point? resolves to (lat, lon) ∈ ValidCoord
    result! = 1 ⟹ coordinates' = coordinates ⌢ ⟨(lat, lon, label, icon)⟩

=head2 add_geojson

  AddGeoJSON
    Î”HTML_OSM
    data?  : GeoJSONStruct ∪ S
    style? : StyleMap ∪ {∅}
    popup? : S ∪ {∅}
  -----------------------------------------
    geojson' = geojson ⌢ ⟨{data, style, popup}⟩

=head2 add_heatmap

  AddHeatmap
    Î”HTML_OSM
    points? : iseq (ℝ x ℝ x [0,1])
  -----------------------------------------
    heatmap_layers' = heatmap_layers ⌢ ⟨{points, radius, blur}⟩

=head2 add_gpx

  AddGPX
    Î”HTML_OSM
    url? : S | url? ≠ ''
  -----------------------------------------
    gpx_tracks' = gpx_tracks ⌢ ⟨url?⟩

=head2 add_chropleth

  AddChoropleth
    Î”HTML_OSM
    features? : iseq GeoFeature
    values?   : S --> ℝ
    key?      : S
    scale?    : iseq S
  -----------------------------------------
    Let min = min(ran values?), max = max(ran values?) ∪ {min+1}
    âˆ€ k ∈ dom values? •
      color(k) = scale?[floor((values?(k)-min)/(max-min) * (#scale?-1))]
    choropleth_layers' = choropleth_layers ⌢ ⟨{features, values, colors, key}⟩

=head2 center

  Center
    Î”HTML_OSM
    point? : (ℝ x ℝ) ∪ S ∪ GeoObject
    result! : {0, 1}
  -----------------------------------------
    result! = 1 ⟺ point? resolves to (lat, lon) ∈ ValidCoord
    result! = 1 ⟹ center' = (lat, lon)

=head2 zoom

  Zoom
    Î”HTML_OSM
    zoom? : Z ∪ {∅}
    zoom! : Z
  -----------------------------------------
    zoom? ≠ ∅ ⟹ ZOOM_MIN <= zoom? <= ZOOM_MAX
    zoom! = (zoom? ≠ ∅ ∧ zoom' = zoom?) ∨ zoom

=head2 onload_render

  OnloadRender
    HTML_OSM
    head! : S
    body! : S
  -----------------------------------------
    (#coordinates + #geojson + #heatmap_layers + #gpx_tracks + #choropleth_layers) > 0
    center ≠ ∅  âˆ¨  âˆƒ valid ∈ coordinates • valid ∈ ValidCoord

=head1 LICENSE AND COPYRIGHT

Copyright 2025-2026 Nigel Horne.

This program is released under the following licence: GPL2
If you use it,
please let me know.

=cut