// Round-trip + edge-detection tests for FlowGraph. The graph
// model is the foundation under the WYSIWYG editor — a bug
// here corrupts every flow the operator opens, so the parser
// gets full coverage of the shipped example shapes.

import 'package:fai_studio_flow_editor/src/model/flow_graph.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  group('FlowGraph parser', () {
    test('parses the canonical hello flow', () {
      const yaml = '''
name: hello

inputs:
  name: text

steps:
  - id: greet
    use: debug.echo@^0
    with:
      message: "Hello, \$inputs.name"

outputs:
  greeting: \$greet.echoed
''';
      final graph = FlowGraph.fromYaml(yaml);
      expect(graph.name, 'hello');
      expect(graph.inputs.keys, contains('name'));
      expect(graph.inputs['name']!.type, 'text');
      expect(graph.steps, hasLength(1));
      expect(graph.steps.first.id, 'greet');
      expect(graph.steps.first.use, 'debug.echo@^0');
      expect(graph.outputs['greeting'], '\$greet.echoed');
    });

    test('detects step-to-step + input-to-step edges', () {
      const yaml = '''
inputs:
  doc: bytes

steps:
  - id: extract
    use: text.extract@^0
    with:
      document: \$inputs.doc
  - id: sum
    use: text.summarize@^0
    with:
      text: \$extract.extracted

outputs:
  result: \$sum.summary
''';
      final graph = FlowGraph.fromYaml(yaml);
      final edges = graph.edges;
      expect(edges, hasLength(3));
      // inputs.doc -> extract.document
      expect(
        edges.any(
          (e) =>
              e.fromKind == EdgeEndpointKind.inputs &&
              e.fromField == 'doc' &&
              e.toId == 'extract' &&
              e.toField == 'document',
        ),
        isTrue,
      );
      // extract.extracted -> sum.text
      expect(
        edges.any(
          (e) =>
              e.fromKind == EdgeEndpointKind.step &&
              e.fromId == 'extract' &&
              e.toId == 'sum' &&
              e.toField == 'text',
        ),
        isTrue,
      );
      // sum.summary -> outputs.result
      expect(
        edges.any(
          (e) =>
              e.fromKind == EdgeEndpointKind.step &&
              e.fromId == 'sum' &&
              e.toKind == EdgeEndpointKind.outputs &&
              e.toField == 'result',
        ),
        isTrue,
      );
    });

    test('flags system.approval steps via isApproval', () {
      const yaml = '''
steps:
  - id: review
    use: system.approval@^0
    with:
      prompt: "Approve?"
''';
      final graph = FlowGraph.fromYaml(yaml);
      expect(graph.steps.single.isApproval, isTrue);
    });

    test('captures leading comment block for round-trip', () {
      const yaml = '''
# Top-of-file comment.
# Spans multiple lines.

name: x
inputs:
  a: text
steps: []
outputs: {}
''';
      final graph = FlowGraph.fromYaml(yaml);
      expect(graph.leadingComment, contains('Top-of-file comment.'));
      final round = graph.toYaml();
      expect(round, contains('Top-of-file comment.'));
    });

    test('round-trips a multi-step flow byte-stably for the shape', () {
      const yaml = '''
name: round-trip

inputs:
  a: text
  b: bytes

steps:
  - id: one
    use: text.extract@^0
    with:
      document: \$inputs.b
  - id: two
    use: llm.chat@^0
    with:
      prompt: \$one.extracted

outputs:
  result: \$two.response
''';
      final first = FlowGraph.fromYaml(yaml);
      final emitted = first.toYaml();
      final second = FlowGraph.fromYaml(emitted);
      // Structural equality — names, IDs, edges
      expect(second.name, first.name);
      expect(second.inputs.keys, first.inputs.keys);
      expect(second.steps.map((s) => s.id), first.steps.map((s) => s.id));
      expect(second.steps.map((s) => s.use), first.steps.map((s) => s.use));
      expect(second.outputs, first.outputs);
      // Edge set identical
      final firstEdges = first.edges
          .map((e) => '${e.fromId}.${e.fromField}>${e.toId}.${e.toField}')
          .toSet();
      final secondEdges = second.edges
          .map((e) => '${e.fromId}.${e.fromField}>${e.toId}.${e.toField}')
          .toSet();
      expect(secondEdges, firstEdges);
    });

    test('tolerates broken YAML — tryParse returns null without throwing', () {
      const bad = '''
inputs: {
  this is not yaml
''';
      expect(FlowGraph.tryParse(bad), isNull);
    });

    test('immutable updates produce independent graphs', () {
      const yaml = '''
steps:
  - id: a
    use: debug.echo@^0
  - id: b
    use: debug.echo@^0
''';
      final graph = FlowGraph.fromYaml(yaml);
      final updated = graph.withStepUpdated(
        'a',
        FlowStep(id: 'a', use: 'debug.echo@^1'),
      );
      expect(graph.steps.first.use, 'debug.echo@^0');
      expect(updated.steps.first.use, 'debug.echo@^1');
    });

    test('handles the extract-with-approval shape (multi-step + approval)', () {
      // Same shape as the shipped example flow — three
      // steps, one of which is the system.approval gate,
      // multi-line prompt with embedded \$step.field refs,
      // outputs that reference multiple steps. If this
      // round-trips structurally the editor is safe on the
      // most complex shipped flow.
      const yaml = '''
name: extract-with-approval

inputs:
  document: bytes
  llm_endpoint: text
  llm_model: text

steps:
  - id: extract
    use: text.extract@^0
    with:
      document: \$inputs.document

  - id: review
    use: system.approval@^0
    with:
      prompt: "Approve before sending to the LLM."
      show: \$extract.extracted

  - id: summarize
    use: llm.chat@^0
    with:
      prompt: "Summarise: \$extract.extracted"
      endpoint: \$inputs.llm_endpoint
      model: \$inputs.llm_model

outputs:
  extracted: \$extract.extracted
  approved_by: \$review.decided_by
  summary: \$summarize.response
''';
      final graph = FlowGraph.fromYaml(yaml);
      expect(graph.steps, hasLength(3));
      expect(graph.steps[1].isApproval, isTrue);
      // Edges: 4 input wires + 3 output wires = 7
      // - inputs.document -> extract.document
      // - extract.extracted -> review.show
      // - extract.extracted -> summarize.prompt
      // - inputs.llm_endpoint -> summarize.endpoint
      // - inputs.llm_model -> summarize.model
      // - extract.extracted -> outputs.extracted
      // - review.decided_by -> outputs.approved_by
      // - summarize.response -> outputs.summary
      // (8 edges total)
      expect(graph.edges.length, greaterThanOrEqualTo(8));
      // Round-trip stability: parse, emit, re-parse — same
      // structural shape.
      final round = FlowGraph.fromYaml(graph.toYaml());
      expect(round.steps.map((s) => s.id), graph.steps.map((s) => s.id));
      expect(round.outputs.keys, graph.outputs.keys);
      expect(round.edges.length, graph.edges.length);
    });
  });
}