module xml

// get_element_by_id returns the first element with the given id, or none if no
// such element exists in the subtree rooted at this node.
pub fn (node XMLNode) get_element_by_id(id string) ?XMLNode {
    // Is this the node we're looking for?
    if attribute_id := node.attributes['id'] {
        if attribute_id == id {
            return node
        }
    }

    if node.children.len == 0 {
        return none
    }

    // Recurse into children
    for child in node.children {
        match child {
            XMLNode {
                if result := child.get_element_by_id(id) {
                    return result
                }
            }
            else {}
        }
    }

    return none
}

// get_elements_by_tag returns all elements with the given tag name in the subtree
// rooted at this node. If there are no such elements, an empty array is returned.
pub fn (node XMLNode) get_elements_by_tag(tag string) []XMLNode {
    mut result := []XMLNode{}

    if node.name == tag {
        result << node
    }

    if node.children.len == 0 {
        return result
    }

    // Recurse into children
    for child in node.children {
        if child is XMLNode {
            result << child.get_elements_by_tag(tag)
        }
    }

    return result
}

// get_elements_by_attribute returns all elements with the given attribute-value pair in
// the subtree rooted at this node. If there are no such elements, an empty array is returned.
pub fn (node XMLNode) get_elements_by_attribute(attribute string, value string) []XMLNode {
    mut result := []XMLNode{}

    if attribute_value := node.attributes[attribute] {
        if attribute_value == value {
            result << node
        }
    }

    if node.children.len == 0 {
        return result
    }

    // Recurse into children
    for child in node.children {
        if child is XMLNode {
            result << child.get_elements_by_attribute(attribute, value)
        }
    }

    return result
}

// get_element_by_id returns the first element with the given id, or none if no
// such element exists.
pub fn (doc XMLDocument) get_element_by_id(id string) ?XMLNode {
    return doc.root.get_element_by_id(id)
}

// get_elements_by_attribute returns all elements with the given attribute-value pair.
// If there are no such elements, an empty array is returned.
pub fn (doc XMLDocument) get_elements_by_attribute(attribute string, value string) []XMLNode {
    return doc.root.get_elements_by_attribute(attribute, value)
}

// get_elements_by_tag returns all elements with the given tag name.
// If there are no such elements, an empty array is returned.
pub fn (doc XMLDocument) get_elements_by_tag(tag string) []XMLNode {
    return doc.root.get_elements_by_tag(tag)
}