import Foundation
import SwiftParser
import SwiftSyntax

/// The main entry point for generating a JSON schema and Markdown documentation
/// for the SourceKit-LSP configuration file format
/// (`.sourcekit-lsp/config.json`) from the Swift type definitions in
/// `SKOptions` Swift module.
public struct ConfigSchemaGen {
  static let projectRoot = URL(fileURLWithPath: #filePath)
    .deletingLastPathComponent()
    .deletingLastPathComponent()
    .deletingLastPathComponent()
    .deletingLastPathComponent()
  static let sourceDir =
    projectRoot
    .appendingPathComponent("Sources")
    .appendingPathComponent("SKOptions")
  static let configSchemaJSONPath =
    projectRoot
    .appendingPathComponent("config.schema.json")
  static let configSchemaDocPath =
    projectRoot
    .appendingPathComponent("Documentation")
    .appendingPathComponent("Configuration File.md")

  public static func generate() throws {
    let sourceFiles = FileManager.default.enumerator(at: sourceDir, includingPropertiesForKeys: nil)!
    let typeNameResolver = TypeDeclResolver()

    for case let fileURL as URL in sourceFiles {
      guard fileURL.pathExtension == "swift" else {
        continue
      }
      let sourceText = try String(contentsOf: fileURL)
      let sourceFile = Parser.parse(source: sourceText)
      typeNameResolver.append(sourceFile)
    }
    let rootTypeDecl = try typeNameResolver.lookupType(fullyQualified: ["SourceKitLSPOptions"])
    let context = OptionSchemaContext(typeNameResolver: typeNameResolver)
    var schema = try context.buildSchema(from: rootTypeDecl)

    // Manually annotate the logging level enum since LogLevel type exists
    // outside of the SKOptions module
    schema["logging"]?["level"]?.kind = .enum(
      OptionTypeSchama.Enum(
        name: "LogLevel",
        cases: ["debug", "info", "default", "error", "fault"].map {
          OptionTypeSchama.Case(name: $0)
        }
      )
    )
    schema["logging"]?["privacyLevel"]?.kind = .enum(
      OptionTypeSchama.Enum(
        name: "PrivacyLevel",
        cases: ["sensitive", "private", "public"].map {
          OptionTypeSchama.Case(name: $0)
        }
      )
    )

    print("Writing schema to \(configSchemaJSONPath.path)")
    try generateJSONSchema(from: schema, context: context).write(to: configSchemaJSONPath)

    print("Writing schema documentation to \(configSchemaDocPath.path)")
    try generateDocumentation(from: schema, context: context).write(
      to: configSchemaDocPath,
      atomically: true,
      encoding: .utf8
    )
  }

  static func generateJSONSchema(from schema: OptionTypeSchama, context: OptionSchemaContext) throws -> Data {
    let schemaBuilder = JSONSchemaBuilder(context: context)
    var jsonSchema = try schemaBuilder.build(from: schema)
    jsonSchema.title = "SourceKit-LSP Configuration"
    jsonSchema.comment = "DO NOT EDIT THIS FILE. This file is generated by \(#fileID)."
    let encoder = JSONEncoder()
    encoder.outputFormatting = [.prettyPrinted, .sortedKeys]
    return try encoder.encode(jsonSchema)
  }

  static func generateDocumentation(from schema: OptionTypeSchama, context: OptionSchemaContext) throws -> String {
    let docBuilder = OptionDocumentBuilder(context: context)
    return try docBuilder.build(from: schema)
  }
}