package linthost

import (
  "strings"
  "testing"

  shimast "github.com/microsoft/typescript-go/shim/ast"
)

// TestNoRedeclareRelatesFirstDefinition verifies the built-in no-redeclare rule
// attaches a related location pointing at the first declaration, so an editor can
// lead the reader from "'x' is already defined." to where the binding first came
// from. The rule already captured the prior declaration's node to build its
// scope map; this pins that the node reaches the finding as a related location
// rather than being discarded.
//
//  1. Lint a source that declares `sample` twice in one scope.
//  2. Assert the redeclaration finding carries exactly one related location whose
//     message names the first definition and whose range precedes the finding.
//
// @evidence contracts/testing.md#behavioral-verification Engine emits exactly one redeclaration finding with exactly one related first-definition location; both complete statement ranges and the related message expose a missing, substituted or misplaced first definition.
// @evidence contracts/testing.md#independent-expectations The two authored var statement spellings and intervening newline establish exact byte ranges independently of Engine output, alongside declaration order and the editor relation contract.
// @evidence contracts/testing.md#distinguishing-cases Same-scope duplicate var owns related information; the corpus fixture no-redeclare.ts supplies nested-shadowing and function-redeclaration controls.
// @evidence contracts/testing.md#execution-ownership TestNoRedeclareRelatesFirstDefinition parseTS parses the two-var source in memory and NewEngineWithResolver runs the no-redeclare rule directly over it; the test reads the finding's RelatedInformation and compares the finding and related byte ranges to authored offsets. No temp project, fix application, consumer install or product host is involved.
func TestNoRedeclareRelatesFirstDefinition(t *testing.T) {
  file := parseTS(t, "var sample = 1;\nvar sample = 2;\nvoid sample;\n")
  findings := NewEngineWithResolver(InlineRuleResolver{
    Rules: RuleConfig{"no-redeclare": SeverityError},
  }).Run([]*shimast.SourceFile{file}, nil)

  var redeclare *Finding
  for _, f := range findings {
    if f.Rule == "no-redeclare" {
      redeclare = f
      break
    }
  }
  if redeclare == nil {
    t.Fatalf("no-redeclare produced no finding; got %d findings", len(findings))
  }
  if len(redeclare.RelatedInformation) != 1 {
    t.Fatalf("want one related location, got %v", redeclare.RelatedInformation)
  }
  related := redeclare.RelatedInformation[0]
  if !strings.Contains(related.Message, "first defined") {
    t.Fatalf("related message should name the first definition, got %q", related.Message)
  }
  if related.End > redeclare.Pos {
    t.Fatalf("the first definition (end %d) should precede the redeclaration (pos %d)", related.End, redeclare.Pos)
  }
  if len(findings) != 1 || related.Pos != 0 || related.End != len("var sample = 1;") ||
    redeclare.Pos != len("var sample = 1;\n") || redeclare.End != len("var sample = 1;\nvar sample = 2;") {
    t.Fatalf("wrong declaration ranges: finding=%+v related=%+v all=%+v", redeclare, related, findings)
  }
}