////
/// Property trees.
///
/// Property trees allow you to organize properties in a tree structure (internally nested maps).
/// The intended use is to store all your properties at the beginning and for the rest of the
/// stylesheet you just get them.
///
/// @group Property trees
///
/// @access public
////

///
/// The maximum depth of resolved iro-prop-ref() references.
///
/// @type number
///
$iro-props-native-assing-max-depth: 2 !default;

///
/// Indicate if property names must start with two dashes (--).
/// This is required if property trees are also used for native CSS custom properties.
///
/// @type bool
///
$iro-props-enforce-double-dashes: true !default;

///
/// Default tree name to use if no name is specified.
///
/// @type string
///
$iro-props-default-tree: 'default' !default;

///
/// List of all created property trees.
///
/// @type list
///
/// @access private
///
$iro-props-trees: ();

/// 
/// Save a property tree. If a tree with the sane name already exists, the trees
/// will be merged.
///
/// @param {map}    $map                            - Map containing properties
/// @param {string} $tree  [$iro-props-default-tree] - ID the map is saved as
/// @param {bool}   $merge [false]                  - If a tree named $tree already exists and this value is set to true, they will be merged. Otherwise an error will be emitted.
///
@mixin iro-props-save($map, $tree: $iro-props-default-tree, $merge: false) {
    $noop: iro-props-save($map, $tree, $merge);
}

/// 
/// Save a property tree.
///
/// @param {map}    $map                            - Map containing properties
/// @param {string} $tree  [$iro-props-default-tree] - ID the map is saved as
/// @param {bool}   $merge [false]                  - If a tree named $tree already exists and this value is set to true, they will be merged. Otherwise an error will be emitted.
///
@function iro-props-save($map, $tree: $iro-props-default-tree, $merge: false) {
    $prop-map: null;

    @if $iro-props-enforce-double-dashes {
        @if not iro-props-validate($map) {
            @error 'Property tree keys must start with two dashes (--). If you don\'t use property trees for native CSS custom properties, set $iro-props-enforce-double-dashes to false.';
        }
    }

    @if map-has-key($iro-props-trees, $tree) {
        @if $merge {
            $map: iro-map-merge-recursive(map-get($iro-props-trees, $tree), $map);
        } @else {
            @error 'Property tree #{inspect($tree)} does already exist.';
        }
    }

    $iro-props-trees: map-merge($iro-props-trees, ($tree: $map)) !global;

    @return null;
}

/// 
/// Delete a property tree.
///
/// @param {string} $tree [$iro-props-default-tree] - ID of the tree to be deleted
///
@mixin iro-props-delete($tree: $iro-props-default-tree) {
    $noop: iro-props-delete($tree);
}

/// 
/// Unset a property tree.
///
/// @param {string} $tree [$iro-props-default-tree] - ID of the tree to be deleted
///
/// @throw If the property tree does not exist
///
@function iro-props-delete($tree: $iro-props-default-tree) {
    @if not map-has-key($iro-props-trees, $tree) {
        @error 'Property tree "#{inspect($tree)}" does not exist.';
    }

    $iro-props-trees: map-remove($iro-props-trees, $tree) !global;

    @return null;
}

/// 
/// Access a whole property or a subsection (i.e. value) of it.
///
/// @param {string | list} $key     [null]                   - Key of the property to read. If this is a list of keys, the map will be traversed in that order.
/// @param {string}        $tree    [$iro-props-default-tree] - ID of the property tree to use
/// @param {any}           $default [null]                   - Default value to return of no match was found. If null, this function will throw an error instead.
///
/// @return {any} Value assigned to property or $default
///
/// @throw If there was no match for $key and $default is null
///
@function iro-props-get($key: (), $tree: $iro-props-default-tree, $default: null) {
    @if not map-has-key($iro-props-trees, $tree) {
        @error 'Unknown tree "#{$tree}".';
    }

    $result: map-get($iro-props-trees, $tree);

    @if type-of($key) == list {
        $stop: false;

        @each $k in $key {
            @if map-has-key($result, $k) and not $stop {
                $result: map-get($result, $k);

                @if type-of($result) == list and nth($result, 1) == 'iro-prop-ref' {
                    @if length($result) == 2 {
                        $result: iro-props-get($tree: nth($result, 2));
                    } @else {
                        $result: iro-props-get(nth($result, 3), nth($result, 2));
                    }
                }
            } @else {
                $stop: true;
            }
        }

        @if $stop {
            $result: null;
        }
    } @else {
        $result: map-get($result, $key);

        @if type-of($result) == list and nth($result, 1) == 'iro-prop-ref' {
            @if length($result) == 2 {
                $result: iro-props-get($tree: nth($result, 2));
            } @else {
                $result: iro-props-get(nth($result, 3), nth($result, 2));
            }
        }
    }

    @if $result == null {
        @if $default == null {
            @error '"#{$key}" is null.';
        } @else {
            @return $default;
        }
    }

    @return $result;
}

/// 
/// Generate a var() function call to get native CSS custom property.
///
/// @param {string | list} $key            - Key of the property to read. If this is a list of keys, the map will be traversed in that order.
/// @param {string | null} $tree    [null] - Optional tree to check if the property actually exists.
/// @param {any}           $default [null] - Default value to return of no match was found.
///
/// @return {string} var()
///
@function iro-props-get-native($key, $tree: null, $default: null) {
    @if $tree != null {
        $noop: iro-props-get($key, $tree, $default);
    }

    $native-var: '';

    @if type-of($key) == list {
        @each $subkey in $key {
            $native-var: $native-var + $subkey;
        }
    } @else {
        $native-var: $key;
    }

    @if $default == null {
        @return var(#{$native-var});
    } @else {
        @return var(#{$native-var}, #{$default});
    }
}

/// 
/// Generate assignments for native CSS custom properties with the values from the specified tree.
///
/// @param {string} $tree [$iro-props-default-tree] - ID of the property tree to use
/// @param {string} $root [()]                     - Sub-tree to use for assignment
///
@mixin iro-props-assign-native($tree: $iro-props-default-tree, $root: (), $skip: (), $prefix: '') {
    $map: iro-props-get($root, $tree);
    $map: map-remove($map, $skip...);

    @if type-of($prefix) == list {
        $prefix: iro-str-implode($prefix)
    }

    @include iro-props-assign-native-internal($map, $prefix);
}

///
/// @access private
///
@mixin iro-props-assign-native-internal($map, $prefix: '', $ref-depth: $iro-props-native-assing-max-depth) {
    @each $key, $value in $map {
        $rd: $ref-depth;
        @if type-of($value) == list and nth($value, 1) == 'iro-prop-ref' {
            @if $ref-depth != 0 {
                $rd: $rd - 1;
                @if length($value) == 2 {
                    $value: iro-props-get($tree: nth($value, 2));
                } @else {
                    $value: iro-props-get(nth($value, 3), nth($value, 2));
                }
            } @else {
                $value: null;
            }
        }
        @if type-of($value) != map {
            #{$prefix + $key}: #{$value};
        } @else {
            @include iro-props-assign-native-internal($value, $prefix + $key, $rd);
        }
    }
}

/// 
/// Validate property names.
///
/// @access private
///
@function iro-props-validate($map) {
    @each $key, $value in $map {
        @if str-index($key, '--') != 1 {
            @return false;
        }

        @if type-of($value) == map {
            @if not iro-props-validate($value) {
                @return false;
            }
        }
    }

    @return true;
}

/// 
/// Generate a reference to another tree. Dereferencing is lazy, so you may specify a tree that hasn't been created yet.
///
/// @param {string}        $tree [$iro-props-default-tree] - ID of the property tree to use
/// @param {string | list} $key                           - Key of the property to read. If this is a list of keys, the map will be traversed in that order.
///
/// @return {list} A special list that let's Ignis know that this is a lazy value.
///
/// @throw If there was no match for $key and $default is null
///
@function iro-props-ref($tree: $iro-props-default-tree, $key: null) {
    @if $key == null {
        @return ('iro-prop-ref' $tree);
    } @else {
        @return ('iro-prop-ref' $tree $key);
    }
}