//
//  Url+Ext.swift
//  gen_html
//
//  Created by Isaac Paul on 9/25/25.
//

import Foundation

extension URL {
  
    enum FileType {
        case directory
        case regularFile
        case other
    }

    func fetchFileType() throws -> FileType {
        let values = try self.resourceValues(forKeys: [.isDirectoryKey, .isRegularFileKey])

        if values.isDirectory == true {
            return .directory
        }
        if values.isRegularFile == true {
            return .regularFile
        }
        if self.hasDirectoryPath {
            return .directory
        }
        return .other
    }
    
    func getRelativePathComponents(
        to toFolder: URL,      // URL A
    ) throws -> [String] {
        // 1) Get path components of A’s directory
        let aDirComponents = toFolder.pathComponents
        // 2) Get path components of B
        let bComponents = self.pathComponents
        
        // Ensure B is actually a prefix of A’s directory
        guard bComponents.count <= aDirComponents.count,
              aDirComponents[0..<bComponents.count] == bComponents[0..<bComponents.count]
        else {
            // B is not a parent of A’s directory; just return destFolder
            throw AppError("Url \(self.absoluteString) is not a relative path to \(toFolder.absoluteString)")
        }
        
        // 3) Compute the “relative” components from B to A’s directory
        let relativeComponents = Array(aDirComponents[bComponents.count...])
        return relativeComponents
    }
    
    func appendRelativePath(
        from fromFolder: URL,      // URL A
        base baseFolder: URL   // URL B
    ) throws -> URL {
        let relativeComponents = try baseFolder.getRelativePathComponents(to: fromFolder)
        
        // 4) Append them one by one onto C
        var result = self
        for comp in relativeComponents {
            result.appendPathComponent(comp)
        }
        
        return result
    }
}