/**
 * Pure derivation of the primary workflow action based on workspace state.
 * No React dependencies — fully testable with plain imports.
 */

export interface WorkflowActionInput {
	phase: string;
	autoActive: boolean;
	autoPaused: boolean;
	onboardingLocked: boolean;
	commandInFlight: string | null;
	bootStatus: string;
	hasMilestones: boolean;
	/** When set, suppresses the action bar if the welcome screen is handling initialization. */
	projectDetectionKind?: string | null;
}

export interface WorkflowAction {
	label: string;
	command: string;
	variant: "default" | "destructive";
}

export interface WorkflowActionResult {
	primary: WorkflowAction | null;
	secondaries: { label: string; command: string }[];
	disabled: boolean;
	disabledReason?: string;
	/** When true, the action represents the all-milestones-complete "New Milestone" state. */
	isNewMilestone: boolean;
}

export function deriveWorkflowAction(
	input: WorkflowActionInput,
): WorkflowActionResult {
	const {
		phase,
		autoActive,
		autoPaused,
		onboardingLocked,
		commandInFlight,
		bootStatus,
		hasMilestones,
		projectDetectionKind,
	} = input;

	// When the project welcome screen is active, it handles the initialization CTA.
	// Suppress the action bar to avoid duplicate/confusing buttons.
	if (
		projectDetectionKind &&
		projectDetectionKind !== "active-sf" &&
		projectDetectionKind !== "empty-sf"
	) {
		return {
			primary: null,
			secondaries: [],
			disabled: true,
			disabledReason: "Project setup pending",
			isNewMilestone: false,
		};
	}

	// Determine disabled state and reason
	let disabled = false;
	let disabledReason: string | undefined;

	if (commandInFlight !== null) {
		disabled = true;
		disabledReason = "Command in progress";
	} else if (bootStatus !== "ready") {
		disabled = true;
		disabledReason = "Workspace not ready";
	} else if (onboardingLocked) {
		disabled = true;
		disabledReason = "Setup required";
	}

	// Derive primary action
	let primary: WorkflowAction | null = null;
	const secondaries: { label: string; command: string }[] = [];
	let isNewMilestone = false;

	if (autoActive && !autoPaused) {
		primary = {
			label: "Stop Autonomous",
			command: "/stop",
			variant: "destructive",
		};
	} else if (autoPaused) {
		primary = {
			label: "Resume Autonomous",
			command: "/autonomous",
			variant: "default",
		};
	} else {
		// Auto is not active
		if (phase === "complete") {
			// All milestones done — surface a distinct "New Milestone" action
			primary = {
				label: "New Milestone",
				command: "/new-milestone",
				variant: "default",
			};
			isNewMilestone = true;
		} else if (phase === "planning") {
			primary = { label: "Plan", command: "/discuss", variant: "default" };
		} else if (phase === "executing" || phase === "summarizing") {
			primary = {
				label: "Start Autonomous",
				command: "/autonomous",
				variant: "default",
			};
		} else if (phase === "pre-planning" && !hasMilestones) {
			primary = {
				label: "Initialize Project",
				command: "/init",
				variant: "default",
			};
		} else if (phase === "blocked") {
			primary = { label: "Blocked", command: "/discuss", variant: "default" };
			disabled = true;
			disabledReason = "Project is blocked — check blockers";
		} else if (phase === "paused") {
			primary = {
				label: "Resume",
				command: "/autonomous",
				variant: "default",
			};
		} else if (phase === "validating-milestone") {
			primary = { label: "Validate", command: "/discuss", variant: "default" };
		} else if (phase === "completing-milestone") {
			primary = {
				label: "Complete Milestone",
				command: "/discuss",
				variant: "default",
			};
		} else if (phase === "needs-discussion") {
			primary = { label: "Discuss", command: "/discuss", variant: "default" };
		} else if (phase === "replanning-slice") {
			primary = { label: "Replan", command: "/discuss", variant: "default" };
		} else {
			primary = { label: "Continue", command: "/discuss", variant: "default" };
		}

		// Add "Step" secondary when auto is not active (not for new milestone — no step concept there)
		if (primary.command !== "/next" && !isNewMilestone) {
			secondaries.push({ label: "Step", command: "/next" });
		}
	}

	return { primary, secondaries, disabled, disabledReason, isNewMilestone };
}