import { parse, ParseError } from 'jsonc-parser';
import * as vscode from 'vscode';
import { ArchifyDiagnostic, isEvidenceError, validate } from '../archify/cli';
import { evidenceMode, runtimeFor } from '../archify/runtime';
import { ModelProblem, isRegistryFile, parseRegistry } from '../model/format';
import { isDecisionFile, parseDecision } from '../model/decisions';
import { prepareDiagram } from '../model/prepare';
import { ModelService } from '../model/service';
import { isArchifyFile } from '../sources/detect';
import { log } from '../util/log';
import path from 'node:path';
import { diagnosticPointer, rangeForPointer, rangeForPointerYaml, yamlSyntaxProblems } from './jsonPointer';
import { DIAGRAM_SCHEMA, REGISTRY_SCHEMA, SchemaChecker, SchemaProblem, readSchemas } from './schemaCheck';

const JSON_LANGUAGES = new Set(['json', 'jsonc']);

function severity(diagnostic: ArchifyDiagnostic, downgradeEvidence: boolean): vscode.DiagnosticSeverity {
  if (downgradeEvidence && isEvidenceError(`${diagnostic.code ?? ''} ${diagnostic.message}`)) {
    return vscode.DiagnosticSeverity.Warning;
  }
  switch (diagnostic.severity) {
    case 'warning':
      return vscode.DiagnosticSeverity.Warning;
    case 'info':
      return vscode.DiagnosticSeverity.Information;
    default:
      return vscode.DiagnosticSeverity.Error;
  }
}

/** Runs `archify validate` on diagram sources and reports into Problems. */
export class DiagnosticsController implements vscode.Disposable {
  private readonly collection = vscode.languages.createDiagnosticCollection('archify');
  private readonly timers = new Map<string, NodeJS.Timeout>();
  private readonly sequence = new Map<string, number>();
  private readonly disposables: vscode.Disposable[];
  private checker: SchemaChecker | undefined;

  constructor(
    private readonly context: vscode.ExtensionContext,
    private readonly models: ModelService,
  ) {
    this.disposables = [
      this.collection,
      models.onDidChangeModel(() => this.revalidateAll()),
      vscode.workspace.onDidOpenTextDocument((doc) => this.schedule(doc, 0)),
      vscode.workspace.onDidChangeTextDocument((event) => {
        if (event.contentChanges.length) this.schedule(event.document, 700);
      }),
      vscode.workspace.onDidSaveTextDocument((doc) => this.schedule(doc, 0)),
      vscode.workspace.onDidCloseTextDocument((doc) => this.clear(doc.uri)),
      vscode.workspace.onDidChangeConfiguration((event) => {
        if (event.affectsConfiguration('archify')) this.revalidateAll();
      }),
    ];
    this.revalidateAll();
  }

  /** Our schemas, compiled on first use. */
  private schemas(): SchemaChecker {
    this.checker ??= new SchemaChecker(readSchemas(vscode.Uri.joinPath(this.context.extensionUri, 'schemas').fsPath));
    return this.checker;
  }

  private schemaDiagnostic(doc: vscode.TextDocument, problem: SchemaProblem): vscode.Diagnostic {
    const diagnostic = new vscode.Diagnostic(
      new vscode.Range(doc.positionAt(problem.from), doc.positionAt(problem.to)),
      problem.message,
      vscode.DiagnosticSeverity.Error,
    );
    diagnostic.source = 'archify';
    return diagnostic;
  }

  private enabled(uri: vscode.Uri): boolean {
    return vscode.workspace.getConfiguration('archify', uri).get<boolean>('validation.enabled', true);
  }

  revalidateAll(): void {
    for (const doc of vscode.workspace.textDocuments) this.schedule(doc, 0);
  }

  private clear(uri: vscode.Uri): void {
    const key = uri.toString();
    clearTimeout(this.timers.get(key));
    this.timers.delete(key);
    this.sequence.set(key, (this.sequence.get(key) ?? 0) + 1);
    this.collection.delete(uri);
  }

  private schedule(doc: vscode.TextDocument, delay: number): void {
    if (!JSON_LANGUAGES.has(doc.languageId) && !isArchifyFile(doc.fileName) && !isRegistryFile(doc.fileName) && !isDecisionFile(doc.fileName)) return;
    const key = doc.uri.toString();
    clearTimeout(this.timers.get(key));
    this.timers.set(key, setTimeout(() => void this.validate(doc), delay));
  }

  private async validate(doc: vscode.TextDocument): Promise<void> {
    const key = doc.uri.toString();
    this.timers.delete(key);
    const seq = (this.sequence.get(key) ?? 0) + 1;
    this.sequence.set(key, seq);

    const text = doc.getText();
    if (!this.enabled(doc.uri) || doc.isClosed) {
      this.collection.delete(doc.uri);
      return;
    }
    if (isRegistryFile(doc.fileName)) {
      await this.validateRegistry(doc, seq);
      return;
    }
    if (isDecisionFile(doc.fileName)) {
      await this.validateDecision(doc, seq);
      return;
    }
    if (isArchifyFile(doc.fileName)) {
      // Nothing else reports YAML syntax errors in .archify files, and a file
      // that does not parse has no diagram to validate yet.
      const problems = yamlSyntaxProblems(text);
      if (problems.length) {
        this.collection.set(
          doc.uri,
          problems.map((problem) => {
            const diagnostic = new vscode.Diagnostic(
              new vscode.Range(doc.positionAt(problem.start), doc.positionAt(problem.end)),
              `YAML: ${problem.message}`,
              vscode.DiagnosticSeverity.Error,
            );
            diagnostic.source = 'archify';
            return diagnostic;
          }),
        );
        return;
      }
    }
    const prepared = await prepareDiagram(this.models, doc.uri, text);
    if (seq !== this.sequence.get(key) || doc.isClosed) return;
    if (!prepared) {
      this.collection.delete(doc.uri);
      return;
    }
    const source = prepared.source;
    const modelDiagnostics = prepared.problems
      .filter((problem) => !problem.file)
      .map((problem) => this.modelDiagnostic(doc, text, source.format, problem));
    if (source.format === 'json') {
      // Leave JSON syntax errors to the JSON language service.
      const syntax: ParseError[] = [];
      parse(text, syntax, { allowTrailingComma: false });
      if (syntax.length) {
        this.collection.delete(doc.uri);
        return;
      }
    }

    if (isArchifyFile(doc.fileName)) {
      // The schema check sees the source as written and answers at once; a
      // file that fails it would fail archify validate the same way, so that
      // runs only on files the schema accepts.
      const schemaProblems = this.schemas().check(text, DIAGRAM_SCHEMA);
      if (schemaProblems.length) {
        this.collection.set(doc.uri, [...modelDiagnostics, ...schemaProblems.map((problem) => this.schemaDiagnostic(doc, problem))]);
        return;
      }
    }

    try {
      const runtime = await runtimeFor(this.context, doc.uri);
      const result = await validate(runtime, source.type, source.json);
      if (seq !== this.sequence.get(key) || doc.isClosed) return;

      if (result.crash) {
        const diagnostic = new vscode.Diagnostic(
          new vscode.Range(0, 0, 0, 0),
          `Archify validation did not complete: ${result.crash.split('\n')[0]}`,
          vscode.DiagnosticSeverity.Error,
        );
        diagnostic.source = 'archify';
        this.collection.set(doc.uri, [diagnostic]);
        return;
      }

      const downgradeEvidence = evidenceMode(doc.uri) === 'fallback';
      this.collection.set(doc.uri, [
        ...modelDiagnostics,
        ...result.diagnostics.map((item) => {
          const pointer = diagnosticPointer(item);
          const offsets = source.format === 'yaml' ? rangeForPointerYaml(text, pointer) : rangeForPointer(text, pointer);
          const range = new vscode.Range(doc.positionAt(offsets.start), doc.positionAt(offsets.end));
          const fix = item.supportedFixes?.[0];
          const diagnostic = new vscode.Diagnostic(
            range,
            fix ? `${item.message}\nFix: ${fix}` : item.message,
            severity(item, downgradeEvidence),
          );
          diagnostic.source = 'archify';
          if (item.code) diagnostic.code = item.code;
          return diagnostic;
        }),
      ]);
    } catch (error) {
      log().error(`Validation failed for ${doc.uri.fsPath}: ${error instanceof Error ? error.message : String(error)}`);
    }
  }

  private modelDiagnostic(doc: vscode.TextDocument, text: string, format: 'yaml' | 'json', problem: ModelProblem): vscode.Diagnostic {
    const offsets = format === 'yaml' ? rangeForPointerYaml(text, problem.pointer) : rangeForPointer(text, problem.pointer);
    const range = problem.line !== undefined && !problem.pointer ? doc.lineAt(Math.min(problem.line, doc.lineCount - 1)).range : new vscode.Range(doc.positionAt(offsets.start), doc.positionAt(offsets.end));
    const diagnostic = new vscode.Diagnostic(range, problem.message, problem.severity === 'warning' ? vscode.DiagnosticSeverity.Warning : vscode.DiagnosticSeverity.Error);
    diagnostic.source = 'archify';
    return diagnostic;
  }

  /** A registry file: its own YAML and element problems, plus duplicates across the model. */
  private async validateDecision(doc: vscode.TextDocument, seq: number): Promise<void> {
    const text = doc.getText();
    const root = await this.models.rootOf(doc.uri);
    const rel = root ? path.relative(root.fsPath, doc.uri.fsPath).split(path.sep).join('/') : path.basename(doc.uri.fsPath);
    const problems: ModelProblem[] = [...parseDecision(text, rel).problems];
    if (root) {
      try {
        const index = await this.models.index(root);
        for (const problem of index.decisions.problems) {
          if (problem.file === rel && !problems.some((p) => p.message === problem.message)) problems.push(problem);
        }
      } catch {
        // The index reports its own failures when the model page opens.
      }
    } else {
      problems.push({ message: `This decision has lost its model: no main.archify above ${path.basename(doc.uri.fsPath)}, so its elements and diagrams cannot be resolved.`, severity: 'warning', line: 0 });
    }
    if (seq !== this.sequence.get(doc.uri.toString()) || doc.isClosed) return;
    this.collection.set(doc.uri, problems.map((problem) => this.modelDiagnostic(doc, text, 'yaml', problem)));
  }

  private async validateRegistry(doc: vscode.TextDocument, seq: number): Promise<void> {
    const text = doc.getText();
    const root = await this.models.rootOf(doc.uri);
    const rel = root ? path.relative(root.fsPath, doc.uri.fsPath) : path.basename(doc.uri.fsPath);
    const problems: ModelProblem[] = [...parseRegistry(text, rel).problems];
    // The schema adds what the parser does not check (types, unknown keys,
    // ids); a file the parser already rejects as a whole gets no second opinion.
    const shapeless = problems.some((p) => /not valid YAML|must be a mapping|needs an "elements" mapping/.test(p.message));
    const schemaProblems = shapeless ? [] : this.schemas().check(text, REGISTRY_SCHEMA);
    if (root) {
      try {
        const index = await this.models.index(root);
        for (const problem of index.registry.problems) {
          if (problem.file === rel && !problems.some((p) => p.message === problem.message)) problems.push(problem);
        }
      } catch {
        // The index reports its own failures when the model page opens.
      }
    } else {
      problems.push({ message: `This registry is not inside a model: no main.archify above ${path.basename(doc.uri.fsPath)}.`, severity: 'warning', line: 0 });
    }
    if (seq !== this.sequence.get(doc.uri.toString()) || doc.isClosed) return;
    this.collection.set(doc.uri, [
      ...problems.map((problem) => this.modelDiagnostic(doc, text, 'yaml', problem)),
      ...schemaProblems.map((problem) => this.schemaDiagnostic(doc, problem)),
    ]);
  }

  dispose(): void {
    for (const timer of this.timers.values()) clearTimeout(timer);
    for (const disposable of this.disposables.splice(0)) disposable.dispose();
  }
}