import { isArrowDown, isArrowUp, isCtrlC, isEnter, isEscape } from "../keys.js";
import type { Component } from "../tui.js";
import { truncateToWidth, visibleWidth, wrapTextWithAnsi } from "../utils.js";

export interface SettingItem {
	/** Unique identifier for this setting */
	id: string;
	/** Display label (left side) */
	label: string;
	/** Optional description shown when selected */
	description?: string;
	/** Current value to display (right side) */
	currentValue: string;
	/** If provided, Enter/Space cycles through these values */
	values?: string[];
	/** If provided, Enter opens this submenu. Receives current value and done callback. */
	submenu?: (currentValue: string, done: (selectedValue?: string) => void) => Component;
}

export interface SettingsListTheme {
	label: (text: string, selected: boolean) => string;
	value: (text: string, selected: boolean) => string;
	description: (text: string) => string;
	cursor: string;
	hint: (text: string) => string;
}

export class SettingsList implements Component {
	private items: SettingItem[];
	private theme: SettingsListTheme;
	private selectedIndex = 0;
	private maxVisible: number;
	private onChange: (id: string, newValue: string) => void;
	private onCancel: () => void;

	// Submenu state
	private submenuComponent: Component | null = null;
	private submenuItemIndex: number | null = null;

	constructor(
		items: SettingItem[],
		maxVisible: number,
		theme: SettingsListTheme,
		onChange: (id: string, newValue: string) => void,
		onCancel: () => void,
	) {
		this.items = items;
		this.maxVisible = maxVisible;
		this.theme = theme;
		this.onChange = onChange;
		this.onCancel = onCancel;
	}

	/** Update an item's currentValue */
	updateValue(id: string, newValue: string): void {
		const item = this.items.find((i) => i.id === id);
		if (item) {
			item.currentValue = newValue;
		}
	}

	invalidate(): void {
		this.submenuComponent?.invalidate?.();
	}

	render(width: number): string[] {
		// If submenu is active, render it instead
		if (this.submenuComponent) {
			return this.submenuComponent.render(width);
		}

		return this.renderMainList(width);
	}

	private renderMainList(width: number): string[] {
		const lines: string[] = [];

		if (this.items.length === 0) {
			lines.push(this.theme.hint("  No settings available"));
			return lines;
		}

		// Calculate visible range with scrolling
		const startIndex = Math.max(
			0,
			Math.min(this.selectedIndex - Math.floor(this.maxVisible / 2), this.items.length - this.maxVisible),
		);
		const endIndex = Math.min(startIndex + this.maxVisible, this.items.length);

		// Calculate max label width for alignment
		const maxLabelWidth = Math.min(30, Math.max(...this.items.map((item) => visibleWidth(item.label))));

		// Render visible items
		for (let i = startIndex; i < endIndex; i++) {
			const item = this.items[i];
			if (!item) continue;

			const isSelected = i === this.selectedIndex;
			const prefix = isSelected ? this.theme.cursor : "  ";
			const prefixWidth = visibleWidth(prefix);

			// Pad label to align values
			const labelPadded = item.label + " ".repeat(Math.max(0, maxLabelWidth - visibleWidth(item.label)));
			const labelText = this.theme.label(labelPadded, isSelected);

			// Calculate space for value
			const separator = "  ";
			const usedWidth = prefixWidth + maxLabelWidth + visibleWidth(separator);
			const valueMaxWidth = width - usedWidth - 2;

			const valueText = this.theme.value(truncateToWidth(item.currentValue, valueMaxWidth, ""), isSelected);

			lines.push(prefix + labelText + separator + valueText);
		}

		// Add scroll indicator if needed
		if (startIndex > 0 || endIndex < this.items.length) {
			const scrollText = `  (${this.selectedIndex + 1}/${this.items.length})`;
			lines.push(this.theme.hint(truncateToWidth(scrollText, width - 2, "")));
		}

		// Add description for selected item
		const selectedItem = this.items[this.selectedIndex];
		if (selectedItem?.description) {
			lines.push("");
			const wrappedDesc = wrapTextWithAnsi(selectedItem.description, width - 4);
			for (const line of wrappedDesc) {
				lines.push(this.theme.description(`  ${line}`));
			}
		}

		// Add hint
		lines.push("");
		lines.push(this.theme.hint("  Enter/Space to change · Esc to cancel"));

		return lines;
	}

	handleInput(data: string): void {
		// If submenu is active, delegate all input to it
		// The submenu's onCancel (triggered by escape) will call done() which closes it
		if (this.submenuComponent) {
			this.submenuComponent.handleInput?.(data);
			return;
		}

		// Main list input handling
		if (isArrowUp(data)) {
			this.selectedIndex = this.selectedIndex === 0 ? this.items.length - 1 : this.selectedIndex - 1;
		} else if (isArrowDown(data)) {
			this.selectedIndex = this.selectedIndex === this.items.length - 1 ? 0 : this.selectedIndex + 1;
		} else if (isEnter(data) || data === " ") {
			this.activateItem();
		} else if (isEscape(data) || isCtrlC(data)) {
			this.onCancel();
		}
	}

	private activateItem(): void {
		const item = this.items[this.selectedIndex];
		if (!item) return;

		if (item.submenu) {
			// Open submenu, passing current value so it can pre-select correctly
			this.submenuItemIndex = this.selectedIndex;
			this.submenuComponent = item.submenu(item.currentValue, (selectedValue?: string) => {
				if (selectedValue !== undefined) {
					item.currentValue = selectedValue;
					this.onChange(item.id, selectedValue);
				}
				this.closeSubmenu();
			});
		} else if (item.values && item.values.length > 0) {
			// Cycle through values
			const currentIndex = item.values.indexOf(item.currentValue);
			const nextIndex = (currentIndex + 1) % item.values.length;
			const newValue = item.values[nextIndex];
			item.currentValue = newValue;
			this.onChange(item.id, newValue);
		}
	}

	private closeSubmenu(): void {
		this.submenuComponent = null;
		// Restore selection to the item that opened the submenu
		if (this.submenuItemIndex !== null) {
			this.selectedIndex = this.submenuItemIndex;
			this.submenuItemIndex = null;
		}
	}
}