import {
	FieldContent,
	FieldContentType,
	isSelectContent,
} from "@prismicio/types-internal/lib/content"
import type { Select } from "@prismicio/types-internal/lib/customtypes"
import {
	DiffChange,
	DiffOperation,
} from "@prismicio/types-internal/lib/customtypes/diff"

import type { NestableMock, Patch } from "../../Mock"
import type { MockConfig } from "../../MockConfig"

const DEFAULT_VALUE = "mock_option"

function random(def: Select): string {
	if (!def.config) return DEFAULT_VALUE

	if (def.config.default_value && Math.random() < 0.5) {
		return def.config.default_value
	}

	if (!def.config.options) return DEFAULT_VALUE

	const index = Math.floor(Math.random() * def.config.options.length)
	return def.config.options[index] || DEFAULT_VALUE
}

export type SelectMockConfig = MockConfig<Select["type"], string>

export const SelectMock: NestableMock<Select, FieldContent, SelectMockConfig> =
	{
		generate(def: Select, config?: SelectMockConfig): FieldContent {
			const value = config?.value || random(def)

			return {
				__TYPE__: FieldContentType,
				value,
				type: "Select",
			}
		},

		applyPatch(data: Patch):
			| {
					result: FieldContent | undefined
			  }
			| undefined {
			if (data.diff.op === DiffOperation.Removed) return { result: undefined }

			if (data.diff.value.type === "Select") {
				const patched = this.patch(
					data.diff,
					isSelectContent(data.content) ? data.content : undefined,
					data.config?.type === "Select" ? data.config : undefined,
				)
				return { result: patched }
			}
			return
		},

		patch(
			diff: DiffChange<Select, Select>,
			_content: FieldContent,
			config?: SelectMockConfig,
		): FieldContent | undefined {
			switch (diff.op) {
				case DiffOperation.Removed:
					return
				case DiffOperation.Updated:
				case DiffOperation.Added:
					return this.generate(diff.value, config)
			}
		},
	}