import { isConfirmed, isDryRun, normalizeMergeRequestLocator, pickAuthInput, request } from '../core.ts'
import { asRecord, readOptionalString, slimMergeRequest } from '../shape.ts'

/**
 * Update a GitLab merge request.
 *
 * Pass `dryRun: true` to preview the request. Live updates require `confirm: true`.
 *
 * @example
 * import updateGitlabMergeRequest from 'kody:@kody/gitlab/merge-requests/update'
 * const preview = await updateGitlabMergeRequest({
 *   project: 'example-group/example-project',
 *   mergeRequestIid: 4,
 *   state_event: 'close',
 *   dryRun: true,
 * })
 */
export default async function updateGitlabMergeRequest(params: Record<string, unknown> = {}) {
	const auth = pickAuthInput(params)
	const { projectId, projectPath, mergeRequestIid } = normalizeMergeRequestLocator(params)
	const body: Record<string, unknown> = {}
	const title = readOptionalString(params.title)
	if (title) body.title = title
	if (params.description !== undefined) {
		body.description = readOptionalString(params.description) ?? ''
	}
	const labels = readOptionalString(params.labels)
	if (labels) body.labels = labels
	const stateEvent = readOptionalString(params.state_event ?? params.stateEvent)
	if (stateEvent) body.state_event = stateEvent
	const targetBranch = readOptionalString(params.target_branch ?? params.targetBranch)
	if (targetBranch) body.target_branch = targetBranch

	if (Object.keys(body).length === 0) {
		throw new Error(
			'Provide at least one field to update (title, description, labels, state_event, target_branch).',
		)
	}

	if (isDryRun(params)) {
		return {
			dryRun: true,
			wouldUpdate: true,
			projectPath,
			mergeRequestIid,
			body,
			auth,
		}
	}

	if (!isConfirmed(params)) {
		throw new Error(
			`Updating ${projectPath}!${mergeRequestIid} requires dryRun: true (preview) or confirm: true (live write).`,
		)
	}

	const response = await request<Record<string, unknown>>({
		...auth,
		method: 'PUT',
		path: `/projects/${projectId}/merge_requests/${mergeRequestIid}`,
		body,
		throwOnError: true,
		confirm: true,
	})

	return {
		...slimMergeRequest(asRecord(response.data)),
		projectPath,
		auth: response.auth,
	}
}