/**
 * GoingsOn - Tasks Kanban Module
 * Board view with drag-and-drop status changes
 */

(function() {
    'use strict';
    const esc = GoingsOn.utils.escapeHtml;
    const escAttr = GoingsOn.utils.escapeAttr;

    const COLUMNS = [
        { status: 'Pending', label: 'Pending' },
        { status: 'Started', label: 'Started' },
        { status: 'Completed', label: 'Completed' },
    ];

    // ============ Rendering ============

    function render(tasks) {
        const board = document.getElementById('task-kanban-board');
        if (!board) return;

        // Group tasks by status
        const grouped = { Pending: [], Started: [], Completed: [] };
        for (const task of tasks) {
            const status = task.status || 'Pending';
            if (grouped[status]) {
                grouped[status].push(task);
            }
        }

        board.innerHTML = COLUMNS.map(col => {
            const colTasks = grouped[col.status] || [];
            return `
                <div class="kanban-column" data-status="${col.status}"
                     ondragover="GoingsOn.tasksKanban.onDragOver(event)"
                     ondragleave="GoingsOn.tasksKanban.onDragLeave(event)"
                     ondrop="GoingsOn.tasksKanban.onDrop(event)">
                    <div class="kanban-column-header">
                        <span>${col.label}</span>
                        <span class="kanban-column-count">${colTasks.length}</span>
                    </div>
                    <div class="kanban-column-body">
                        ${colTasks.length === 0
                            ? '<div class="empty-state empty-state--compact">No tasks</div>'
                            : colTasks.map(t => renderCard(t)).join('')}
                    </div>
                </div>`;
        }).join('');
    }

    function renderCard(task) {
        const displayDesc = task.displayDescription || task.description;
        const progress = task.subtaskProgress ?? 0;

        return `
            <div class="card kanban-card priority-${task.priority.toLowerCase()}"
                 draggable="true" data-task-id="${escAttr(task.id)}" data-status="${task.status}"
                 ondragstart="GoingsOn.tasksKanban.onDragStart(event)"
                 ondragend="GoingsOn.tasksKanban.onDragEnd(event)"
                 onclick="GoingsOn.tasks.openSubtasks('${escAttr(task.id)}')"
                 oncontextmenu="GoingsOn.contextMenus.showTask(event, '${escAttr(task.id)}')">
                <div class="kanban-card-title">${esc(displayDesc)}</div>
                <div class="kanban-card-meta">
                    ${task.projectName ? `<span class="kanban-card-project">${esc(task.projectName)}</span>` : ''}
                    ${task.dueFormatted ? `<span class="kanban-card-due ${task.isOverdue ? 'overdue' : ''}">${esc(task.dueFormatted)}</span>` : ''}
                </div>
                ${task.subtaskCount > 0 ? `<div class="progress-bar-mini"><div class="progress-fill" style="width:${progress}%"></div></div>` : ''}
            </div>`;
    }

    // ============ Drag and Drop ============

    let draggedTaskId = null;

    function onDragStart(e) {
        draggedTaskId = e.target.dataset.taskId;
        e.target.classList.add('dragging');
        e.dataTransfer.effectAllowed = 'move';
        e.dataTransfer.setData('text/plain', draggedTaskId);
    }

    function onDragEnd(e) {
        e.target.classList.remove('dragging');
        draggedTaskId = null;
        // Remove all drag-over highlights
        document.querySelectorAll('.kanban-column.drag-over').forEach(col => {
            col.classList.remove('drag-over');
        });
    }

    function onDragOver(e) {
        e.preventDefault();
        e.dataTransfer.dropEffect = 'move';
        const column = e.target.closest('.kanban-column');
        if (column) column.classList.add('drag-over');
    }

    function onDragLeave(e) {
        const column = e.target.closest('.kanban-column');
        if (column && !column.contains(e.relatedTarget)) {
            column.classList.remove('drag-over');
        }
    }

    async function onDrop(e) {
        e.preventDefault();
        const column = e.target.closest('.kanban-column');
        if (!column) return;
        column.classList.remove('drag-over');

        const taskId = e.dataTransfer.getData('text/plain');
        if (!taskId) return;

        const newStatus = column.dataset.status;
        const tasks = GoingsOn.state.tasks || [];
        const task = tasks.find(t => t.id === taskId);
        if (!task || task.status === newStatus) return;

        await handleDrop(taskId, task, newStatus);
    }

    async function handleDrop(taskId, task, newStatus) {
        try {
            if (newStatus === 'Started') {
                await GoingsOn.api.tasks.start(taskId);
                GoingsOn.ui.showToast('Task started!', 'success');
            } else if (newStatus === 'Completed') {
                await GoingsOn.api.tasks.complete(taskId);
                GoingsOn.ui.showToast('Task completed!', 'success');
            } else if (newStatus === 'Pending') {
                // Move back to pending via update
                await GoingsOn.api.tasks.update(taskId, {
                    description: task.description,
                    projectId: task.project_id || task.projectId || null,
                    status: 'Pending',
                    priority: task.priority,
                    due: task.due || null,
                    tags: task.tags || [],
                    recurrence: task.recurrence || 'None',
                    contactId: task.contactId || null,
                    milestoneId: task.milestoneId || null,
                });
                GoingsOn.ui.showToast('Task moved to Pending', 'success');
            }
            // Re-fetch to get accurate server state (recurrence, etc.)
            await GoingsOn.tasks.load();
        } catch (err) {
            GoingsOn.ui.showToast(GoingsOn.utils.getErrorMessage(err, 'Failed to update task'), 'error');
            // Re-render to revert visual position
            await GoingsOn.tasks.load();
        }
    }

    // ============ Populate Namespace ============

    GoingsOn.tasksKanban = {
        render,
        onDragStart,
        onDragEnd,
        onDragOver,
        onDragLeave,
        onDrop,
    };

})();