import * as path from 'node:path/posix';
/**
 * Entry point file names in priority order.
 * The first match found wins.
 */
const ENTRY_POINT_NAMES = [
    'index.ts',
    'index.tsx',
    'index.js',
    'main.ts',
    'main.py',
    'App.tsx',
    'App.ts',
    'app.ts',
    'app.py',
    'main.go',
    'main.rs',
    'Main.java',
];
/**
 * Finds the entry point node from the list of file nodes.
 *
 * Strategy:
 * 1. Check for common entry point file names (with and without src/ prefix)
 * 2. Fallback: use the file with the most outgoing import edges
 */
export function findEntryPoint(fileNodes, edges) {
    if (fileNodes.length === 0)
        return undefined;
    // Try each entry point name in priority order
    for (const entryName of ENTRY_POINT_NAMES) {
        const match = fileNodes.find(node => {
            const basename = path.basename(node.id);
            if (basename !== entryName)
                return false;
            // Match root-level or src/-level files
            const dir = path.dirname(node.id);
            return dir === '.' || dir === 'src' || node.id === entryName || node.id === `src/${entryName}`;
        });
        if (match)
            return match;
    }
    // Fallback: file with the most outgoing import edges
    const importEdges = edges.filter(e => e.type === 'imports');
    let maxOutgoing = -1;
    let bestNode;
    for (const node of fileNodes) {
        const outgoing = importEdges.filter(e => e.source === node.id).length;
        if (outgoing > maxOutgoing) {
            maxOutgoing = outgoing;
            bestNode = node;
        }
    }
    return bestNode;
}
/**
 * Finds the layer a file node belongs to.
 */
function getNodeLayer(nodeId, layers) {
    return layers.find(layer => layer.nodeIds.includes(nodeId));
}
/**
 * Gets child node IDs (functions/classes) that belong to a file.
 * These are nodes whose ID starts with the file path followed by "::".
 */
function getChildNodeIds(fileNodeId, allNodes) {
    const prefix = fileNodeId + '::';
    return allNodes
        .filter(n => n.id.startsWith(prefix))
        .map(n => n.id);
}
/**
 * Generates a description for a tour step based on the node's summary and layer.
 */
function generateDescription(node, layer) {
    const layerInfo = layer ? ` (${layer.name} layer)` : '';
    if (node.summary) {
        return `${node.summary}${layerInfo}`;
    }
    return `Source file${layerInfo}`;
}
/**
 * Performs BFS from the entry point following import edges.
 * Returns file node IDs in BFS order (no duplicates).
 */
function bfsFromEntryPoint(entryPointId, fileNodes, edges, maxSteps) {
    const fileNodeIds = new Set(fileNodes.map(n => n.id));
    const importEdges = edges.filter(e => e.type === 'imports');
    const visited = new Set();
    const queue = [entryPointId];
    const result = [];
    visited.add(entryPointId);
    while (queue.length > 0 && result.length < maxSteps) {
        const current = queue.shift();
        result.push(current);
        if (result.length >= maxSteps)
            break;
        // Find all files imported by the current file
        const neighbors = importEdges
            .filter(e => e.source === current)
            .map(e => e.target)
            .filter(target => fileNodeIds.has(target) && !visited.has(target));
        for (const neighbor of neighbors) {
            visited.add(neighbor);
            queue.push(neighbor);
        }
    }
    return result;
}
/**
 * Supplements BFS results with representative files from uncovered layers.
 * Picks the file with the most edges (most connected) from each uncovered layer.
 */
function supplementWithLayers(bfsFileIds, fileNodes, edges, layers, maxSteps) {
    if (layers.length === 0)
        return bfsFileIds;
    const coveredIds = new Set(bfsFileIds);
    // Find which layers are already covered
    const coveredLayerIds = new Set();
    for (const fileId of bfsFileIds) {
        const layer = getNodeLayer(fileId, layers);
        if (layer)
            coveredLayerIds.add(layer.id);
    }
    const result = [...bfsFileIds];
    const fileNodeIds = new Set(fileNodes.map(n => n.id));
    // For each uncovered layer, pick the most connected file
    for (const layer of layers) {
        if (result.length >= maxSteps)
            break;
        if (coveredLayerIds.has(layer.id))
            continue;
        // Get file nodes in this layer
        const layerFileIds = layer.nodeIds.filter(id => fileNodeIds.has(id) && !coveredIds.has(id));
        if (layerFileIds.length === 0)
            continue;
        // Pick the file with the most edges (incoming + outgoing)
        let bestFileId = layerFileIds[0];
        let maxEdges = 0;
        for (const fileId of layerFileIds) {
            const edgeCount = edges.filter(e => e.source === fileId || e.target === fileId).length;
            if (edgeCount > maxEdges) {
                maxEdges = edgeCount;
                bestFileId = fileId;
            }
        }
        result.push(bestFileId);
        coveredIds.add(bestFileId);
        coveredLayerIds.add(layer.id);
    }
    return result;
}
/**
 * Generates a guided tour through the project architecture.
 *
 * Tour generation strategy:
 * 1. Find entry point (index.ts, main.py, App.tsx, etc.)
 * 2. Follow import chain from entry point (BFS, max 10 steps)
 * 3. Each step covers a new layer or key component
 * 4. Generate title from file/function name, description from structure
 *
 * If BFS produces fewer than 5 steps, supplements with one representative
 * file from each layer not yet covered (most connected file).
 *
 * @param nodes - All graph nodes
 * @param edges - All graph edges (used to follow import chains)
 * @param layers - Detected architectural layers
 * @returns Ordered array of tour steps
 */
export function buildTour(nodes, edges, layers) {
    // Edge cases
    if (nodes.length === 0)
        return [];
    const fileNodes = nodes.filter(n => n.type === 'file');
    if (fileNodes.length === 0)
        return [];
    const maxSteps = 10;
    const minBfsSteps = 5;
    // Find entry point
    const entryPoint = findEntryPoint(fileNodes, edges);
    if (!entryPoint)
        return [];
    // BFS from entry point
    let tourFileIds = bfsFromEntryPoint(entryPoint.id, fileNodes, edges, maxSteps);
    // Supplement with layer representatives if BFS is short
    if (tourFileIds.length < minBfsSteps) {
        tourFileIds = supplementWithLayers(tourFileIds, fileNodes, edges, layers, maxSteps);
    }
    // Generate tour steps
    const steps = [];
    for (let i = 0; i < tourFileIds.length; i++) {
        const fileId = tourFileIds[i];
        const fileNode = fileNodes.find(n => n.id === fileId);
        if (!fileNode)
            continue;
        const layer = getNodeLayer(fileId, layers);
        const childIds = getChildNodeIds(fileId, nodes);
        steps.push({
            order: i + 1,
            title: fileNode.name,
            description: generateDescription(fileNode, layer),
            nodeIds: [fileId, ...childIds],
        });
    }
    return steps;
}