feat: form_type and styling metadata arguments added

docs/data-sources/parameter.md

@@ -145,10 +145,12 @@ data "coder_parameter" "home_volume_size" {
 - `description` (String) Describe what this parameter does.
 - `display_name` (String) The displayed name of the parameter as it will appear in the interface.
 - `ephemeral` (Boolean) The value of an ephemeral parameter will not be preserved between consecutive workspace builds.
+- `form_type` (String) The type of this parameter. Must be one of: [radio, slider, input, dropdown, checkbox, switch, multi-select, tag-select, textarea, error].
 - `icon` (String) A URL to an icon that will display in the dashboard. View built-in icons [here](https://github.com/coder/coder/tree/main/site/static/icon). Use a built-in icon with `"${data.coder_workspace.me.access_url}/icon/<path>"`.
 - `mutable` (Boolean) Whether this value can be changed after workspace creation. This can be destructive for values like region, so use with caution!
 - `option` (Block List) Each `option` block defines a value for a user to select from. (see [below for nested schema](#nestedblock--option))
 - `order` (Number) The order determines the position of a template parameter in the UI/CLI presentation. The lowest order is shown first and parameters with equal order are sorted by name (ascending order).
+- `styling` (String) JSON encoded string containing the metadata for controlling the appearance of this parameter in the UI. This option is purely cosmetic and does not affect the function of the parameter in terraform.
 - `type` (String) The type of this parameter. Must be one of: `"number"`, `"string"`, `"bool"`, or `"list(string)"`.
 - `validation` (Block List, Max: 1) Validate the input of a parameter. (see [below for nested schema](#nestedblock--validation))
 

provider/formtype.go

@@ -0,0 +1,148 @@
+package provider
+
+import (
+	"slices"
+
+	"golang.org/x/xerrors"
+)
+
+// OptionType is a type of option that can be used in the 'type' argument of
+// a parameter. These should match types as defined in terraform:
+//
+//	https://developer.hashicorp.com/terraform/language/expressions/types
+//
+// The value have to be string literals, as type constraint keywords are not
+// supported in providers.
+type OptionType string
+
+const (
+	OptionTypeString     OptionType = "string"
+	OptionTypeNumber     OptionType = "number"
+	OptionTypeBoolean    OptionType = "bool"
+	OptionTypeListString OptionType = "list(string)"
+)
+
+func OptionTypes() []OptionType {
+	return []OptionType{
+		OptionTypeString,
+		OptionTypeNumber,
+		OptionTypeBoolean,
+		OptionTypeListString,
+	}
+}
+
+// ParameterFormType is the list of supported form types for display in
+// the Coder "create workspace" form. These form types are functional as well
+// as cosmetic. Refer to `formTypeTruthTable` for the allowed pairings.
+// For example, "multi-select" has the type "list(string)" but the option
+// values are "string".
+type ParameterFormType string
+
+const (
+	ParameterFormTypeDefault     ParameterFormType = ""
+	ParameterFormTypeRadio       ParameterFormType = "radio"
+	ParameterFormTypeSlider      ParameterFormType = "slider"
+	ParameterFormTypeInput       ParameterFormType = "input"
+	ParameterFormTypeDropdown    ParameterFormType = "dropdown"
+	ParameterFormTypeCheckbox    ParameterFormType = "checkbox"
+	ParameterFormTypeSwitch      ParameterFormType = "switch"
+	ParameterFormTypeMultiSelect ParameterFormType = "multi-select"
+	ParameterFormTypeTagSelect   ParameterFormType = "tag-select"
+	ParameterFormTypeTextArea    ParameterFormType = "textarea"
+	ParameterFormTypeError       ParameterFormType = "error"
+)
+
+// ParameterFormTypes should be kept in sync with the enum list above.
+func ParameterFormTypes() []ParameterFormType {
+	return []ParameterFormType{
+		// Intentionally omit "ParameterFormTypeDefault" from this set.
+		// It is a valid enum, but will always be mapped to a real value when
+		// being used.
+		ParameterFormTypeRadio,
+		ParameterFormTypeSlider,
+		ParameterFormTypeInput,
+		ParameterFormTypeDropdown,
+		ParameterFormTypeCheckbox,
+		ParameterFormTypeSwitch,
+		ParameterFormTypeMultiSelect,
+		ParameterFormTypeTagSelect,
+		ParameterFormTypeTextArea,
+		ParameterFormTypeError,
+	}
+}
+
+// formTypeTruthTable is a map of [`type`][`optionCount` > 0] to `form_type`.
+// The first value in the slice is the default value assuming `form_type` is
+// not specified.
+//
+// The boolean key indicates whether the `options` field is specified.
+// | Type              | Options | Specified Form Type | form_type      | Notes                          |
+// |-------------------|---------|---------------------|----------------|--------------------------------|
+// | `string` `number` | Y       |                     | `radio`        |                                |
+// | `string` `number` | Y       | `dropdown`          | `dropdown`     |                                |
+// | `string` `number` | N       |                     | `input`        |                                |
+// | `string`          | N       | 'textarea'          | `textarea`     |                                |
+// | `number`          | N       | 'slider'            | `slider`       | min/max validation             |
+// | `bool`            | Y       |                     | `radio`        |                                |
+// | `bool`            | N       |                     | `checkbox`     |                                |
+// | `bool`            | N       | `switch`            | `switch`       |                                |
+// | `list(string)`    | Y       |                     | `radio`        |                                |
+// | `list(string)`    | N       |                     | `tag-select`   |                                |
+// | `list(string)`    | Y       | `multi-select`      | `multi-select` | Option values will be `string` |
+var formTypeTruthTable = map[OptionType]map[bool][]ParameterFormType{
+	OptionTypeString: {
+		true:  {ParameterFormTypeRadio, ParameterFormTypeDropdown},
+		false: {ParameterFormTypeInput, ParameterFormTypeTextArea},
+	},
+	OptionTypeNumber: {
+		true:  {ParameterFormTypeRadio, ParameterFormTypeDropdown},
+		false: {ParameterFormTypeInput, ParameterFormTypeSlider},
+	},
+	OptionTypeBoolean: {
+		true:  {ParameterFormTypeRadio},
+		false: {ParameterFormTypeCheckbox, ParameterFormTypeSwitch},
+	},
+	OptionTypeListString: {
+		true:  {ParameterFormTypeRadio, ParameterFormTypeMultiSelect},
+		false: {ParameterFormTypeTagSelect},
+	},
+}
+
+// ValidateFormType handles the truth table for the valid set of `type` and
+// `form_type` options.
+// The OptionType is also returned because it is possible the 'type' of the
+// 'value' & 'default' fields is different from the 'type' of the options.
+// The use case is when using multi-select. The options are 'string' and the
+// value is 'list(string)'.
+func ValidateFormType(paramType OptionType, optionCount int, specifiedFormType ParameterFormType) (OptionType, ParameterFormType, error) {
+	allowed, ok := formTypeTruthTable[paramType][optionCount > 0]
+	if !ok || len(allowed) == 0 {
+		return paramType, specifiedFormType, xerrors.Errorf("value type %q is not supported for 'form_types'", paramType)
+	}
+
+	if specifiedFormType == ParameterFormTypeDefault {
+		// handle the default case
+		specifiedFormType = allowed[0]
+	}
+
+	if !slices.Contains(allowed, specifiedFormType) {
+		return paramType, specifiedFormType, xerrors.Errorf("value type %q is not supported for 'form_types'", specifiedFormType)
+	}
+
+	// This is the only current special case. If 'multi-select' is selected, the type
+	// of 'value' and an options 'value' are different. The type of the parameter is
+	// `list(string)` but the type of the individual options is `string`.
+	if paramType == OptionTypeListString && specifiedFormType == ParameterFormTypeMultiSelect {
+		return OptionTypeString, ParameterFormTypeMultiSelect, nil
+	}
+
+	return paramType, specifiedFormType, nil
+}
+
+func toStrings[A ~string](l []A) []string {
+	var r []string
+	for _, v := range l {
+		r = append(r, string(v))
+	}
+	return r
+}