feat: create BaseButton component (#1123)

Co-authored-by: Dominik Pschenitschni <mail@celement.de>
Reviewed-on: https://kolaente.dev/vikunja/frontend/pulls/1123
Reviewed-by: konrad <k@knt.li>
Co-authored-by: Dominik Pschenitschni <dpschen@noreply.kolaente.de>
Co-committed-by: Dominik Pschenitschni <dpschen@noreply.kolaente.de>

src/components/base/BaseButton.vue

@@ -0,0 +1,118 @@
+<template>
+	<component
+		:is="componentNodeName"
+		class="base-button"
+		:class="{ 'base-button--type-button': isButton }"
+		v-bind="elementBindings"
+		:disabled="disabled || undefined"
+	>
+		<slot />
+	</component>
+</template>
+
+<script lang="ts">
+// see https://v3.vuejs.org/api/sfc-script-setup.html#usage-alongside-normal-script
+export default {
+  inheritAttrs: false,
+}
+</script>
+
+<script lang="ts" setup>
+// this component removes styling differences between links / vue-router links and button elements
+// by doing so we make it easy abstract the functionality from style and enable easier and semantic
+// correct button and link usage. Also see: https://css-tricks.com/a-complete-guide-to-links-and-buttons/#accessibility-considerations
+
+// the component tries to heuristically determine what it should be checking the props (see the
+// componentNodeName and elementBindings ref for this).
+
+// NOTE: Do NOT use buttons with @click to push routes. => Use router-links instead!
+
+import { ref, watchEffect, computed, useAttrs, PropType } from 'vue'
+
+const BASE_BUTTON_TYPES_MAP =  Object.freeze({
+  button: 'button',
+  submit: 'submit',
+})
+
+type BaseButtonTypes = keyof typeof BASE_BUTTON_TYPES_MAP
+
+const props = defineProps({
+	type: {
+		type: String as PropType<BaseButtonTypes>,
+		default: 'button',
+	},
+	disabled: {
+		type: Boolean,
+		default: false,
+	},
+})
+
+
+const componentNodeName = ref<Node['nodeName']>('button')
+interface ElementBindings {
+	type?: string;
+	rel?: string,
+}
+
+const elementBindings = ref({})
+
+const attrs = useAttrs()
+watchEffect(() => {
+	// by default this component is a button element with the attribute of the type "button" (default prop value)
+	let nodeName = 'button'
+	let bindings: ElementBindings = {type: props.type}
+
+	// if we find a "to" prop we set it as router-link
+	if ('to' in attrs) {
+		nodeName = 'router-link'
+		bindings = {}
+	}
+
+	// if there is a href we assume the user wants an external link via a link element
+	// we also set the attribute rel to "noopener" but make it possible to overwrite this by the user.
+	if ('href' in attrs) {
+		nodeName = 'a'
+		bindings = {rel: 'noopener'}
+	}
+
+	componentNodeName.value = nodeName
+	elementBindings.value = {
+		...bindings,
+		...attrs,
+	}
+})
+
+const isButton = computed(() => componentNodeName.value === 'button')
+</script>
+
+<style lang="scss">
+// NOTE: we do not use scoped styles to reduce specifity and make it easy to overwrite
+
+// We reset the default styles of a button element to enable easier styling
+:where(.base-button--type-button) {
+	border: 0;
+	margin: 0;
+	padding: 0;
+	text-decoration: none;
+	background-color: transparent;
+	text-align: center;
+	appearance: none;
+}
+
+:where(.base-button) {
+	cursor: pointer;
+	display: block;
+	color: inherit;
+	font: inherit;
+	user-select: none;
+	pointer-events: auto; // disable possible resets
+
+	&:focus {
+		outline: transparent;
+	}
+
+	&[disabled] {
+		cursor: default;
+	}
+}
+</style>