package appbackup

import (
	"go/ast"
	"go/parser"
	"go/token"
	"os"
	"path/filepath"
	"testing"
	"time"
)

// R-379/R-381. An undo copy used to derive its stack name by trimming only the engine suffix, so
// `pre-restore-20260822T140924Z-docmost-postgres.sql` yielded the phantom stack
// `pre-restore-20260822T140924Z-docmost`. That name reaches web.buildAppBackupRows' `dbStacks` map
// as a KEY.
//
// MEASURED ON THE LIVE PAGE 2026-08-22 BEFORE CHANGING ANYTHING: /backups/apps contained ZERO
// `pre-restore` strings while four such files sat on disk, because that function iterates DEPLOYED
// apps and only reads the map by key. So the phantom never renders TODAY — the visible-row defect
// does not reproduce, and this test does not claim it did. What it pins is the naming, so any future
// code that RANGES over that map cannot surface a stack that does not exist.
func TestUndoCopyResolvesToItsOwnApp(t *testing.T) {
	dir := t.TempDir()
	write := func(name string) {
		if err := os.WriteFile(filepath.Join(dir, name), []byte("-- PostgreSQL database dump\nCREATE TABLE x();\n"), 0o644); err != nil {
			t.Fatal(err)
		}
	}
	write("docmost-postgres.sql")
	write("pre-restore-20260822T140924Z-docmost-postgres.sql")
	write("pre-restore-20260822T142418Z-bookstack-mariadb.sql")

	files, err := ListDumpFiles(dir, nil)
	if err != nil {
		t.Fatal(err)
	}
	byName := map[string]DumpFileInfo{}
	for _, f := range files {
		byName[f.FileName] = f
	}
	if len(byName) != 3 {
		t.Fatalf("expected 3 dumps listed, got %d", len(byName))
	}

	own := byName["docmost-postgres.sql"]
	if own.StackName != "docmost" || own.IsUndo {
		t.Errorf("the app's own dump must be stack=docmost and NOT an undo; got stack=%q isUndo=%v", own.StackName, own.IsUndo)
	}

	u := byName["pre-restore-20260822T140924Z-docmost-postgres.sql"]
	if u.StackName != "docmost" {
		t.Errorf("an undo copy must resolve to the app it belongs to, not a phantom; got %q", u.StackName)
	}
	if !u.IsUndo {
		t.Error("an undo copy must be marked as one — its visibility is a recorded decision, so it must be NAMED rather than hidden")
	}
	if u.DBType != DBTypePostgres {
		t.Errorf("the engine must still be parsed; got %q", u.DBType)
	}
	want, _ := time.Parse("20060102T150405Z", "20260822T140924Z")
	if !u.UndoAt.Equal(want) {
		t.Errorf("UndoAt = %v, want %v", u.UndoAt, want)
	}

	m := byName["pre-restore-20260822T142418Z-bookstack-mariadb.sql"]
	if m.StackName != "bookstack" || !m.IsUndo || m.DBType != DBTypeMariaDB {
		t.Errorf("mariadb undo copy mis-parsed: stack=%q isUndo=%v type=%q", m.StackName, m.IsUndo, m.DBType)
	}
}

// A file that merely starts with the prefix but is not the shape writeSafetyDump writes must be left
// alone rather than guessed at.
func TestUndoPrefixWithoutAStampIsNotTreatedAsAnUndo(t *testing.T) {
	if base, stamp, ok := trimUndoPrefix("pre-restore-nostamp"); ok {
		t.Errorf("a prefix with no stamp separator must not parse as an undo; got base=%q stamp=%q", base, stamp)
	}
	if base, _, ok := trimUndoPrefix("docmost-postgres"); ok || base != "docmost-postgres" {
		t.Errorf("a normal dump must flow through unchanged; got base=%q ok=%v", base, ok)
	}
}

// R-381, AT THE LAYER THE LEAK LIVES IN.
//
// WHY THIS TEST EXISTS AND THE BEHAVIOURAL ONE WAS NOT ENOUGH — recorded because it was caught by a
// red-proof that PASSED. The sibling test in internal/backup asserts that the reconstitution's
// customer sentence carries no engine output, but it injects at `m.importDBDump`, i.e. BELOW
// ImportDump. Re-adding the stderr to ImportDump's own fmt.Errorf therefore did not fail it. The
// leak's home is this function, so the guard belongs here.
//
// ImportDump shells out to docker, so its failure path cannot be driven in a unit test. What CAN be
// pinned is the thing the mutation changes: the error it constructs must not reference the captured
// stderr. AST, not strings.Contains — a commented-out reference still contains the string.
func TestImportDumpErrorDoesNotCarryEngineStderr(t *testing.T) {
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "dbdump.go", nil, 0)
	if err != nil {
		t.Fatal(err)
	}
	var body *ast.BlockStmt
	for _, d := range f.Decls {
		if fn, ok := d.(*ast.FuncDecl); ok && fn.Name.Name == "ImportDump" && fn.Body != nil {
			body = fn.Body
		}
	}
	if body == nil {
		t.Fatal("ImportDump not found — this guard can no longer prove anything")
	}

	// Find the name the stderr text is captured into, so the test tracks a rename instead of
	// silently passing when the variable is called something else.
	stderrVar := ""
	ast.Inspect(body, func(n ast.Node) bool {
		as, ok := n.(*ast.AssignStmt)
		if !ok || len(as.Lhs) != 1 || len(as.Rhs) != 1 {
			return true
		}
		call, ok := as.Rhs[0].(*ast.CallExpr)
		if !ok {
			return true
		}
		// strings.TrimSpace(stderr.String())
		if sel, ok := call.Fun.(*ast.SelectorExpr); ok && sel.Sel.Name == "TrimSpace" {
			if id, ok := as.Lhs[0].(*ast.Ident); ok {
				stderrVar = id.Name
			}
		}
		return true
	})
	if stderrVar == "" {
		t.Fatal("could not find where ImportDump captures the engine stderr — the guard cannot aim")
	}

	var leaked bool
	ast.Inspect(body, func(n ast.Node) bool {
		ret, ok := n.(*ast.ReturnStmt)
		if !ok {
			return true
		}
		for _, r := range ret.Results {
			call, ok := r.(*ast.CallExpr)
			if !ok {
				continue
			}
			sel, ok := call.Fun.(*ast.SelectorExpr)
			if !ok || sel.Sel.Name != "Errorf" {
				continue
			}
			for _, arg := range call.Args {
				if id, ok := arg.(*ast.Ident); ok && id.Name == stderrVar {
					leaked = true
				}
			}
		}
		return true
	})
	if leaked {
		t.Fatalf("ImportDump's returned error passes %q (the engine stderr) — that text reaches the customer's dashboard. "+
			"Measured 2026-08-22 at 615 bytes on MariaDB, whose middle was rows out of the customer's own database. "+
			"The full text belongs in the operator log, which this function already writes.", stderrVar)
	}

	// POSITIVE CONTROL for the "it is still logged" half: the operator must not lose the diagnostic.
	var logged bool
	ast.Inspect(body, func(n ast.Node) bool {
		call, ok := n.(*ast.CallExpr)
		if !ok {
			return true
		}
		if sel, ok := call.Fun.(*ast.SelectorExpr); ok && sel.Sel.Name == "Printf" {
			for _, arg := range call.Args {
				if id, ok := arg.(*ast.Ident); ok && id.Name == stderrVar {
					logged = true
				}
			}
		}
		return true
	})
	if !logged {
		t.Error("the engine stderr is no longer logged either — the diagnostic must be ADDED to the operator log, not removed from everywhere")
	}
}

// R-361, AT THE LAYER THE DESTINATION IS HONOURED.
//
// WHY THIS EXISTS — recorded because a red-proof PASSED without it, for the second session running.
// The behavioural tests in internal/backup inject `m.safetyDumpFn`, so the REAL DumpOneTo never runs
// there: making DumpOneTo ignore its `finalPath` and write the canonical name anyway did not fail a
// single one of them. DumpOneTo shells out to docker, so its write path cannot be driven in a unit
// test; what CAN be pinned is the thing the mutation changes.
//
// TWO PROPERTIES, both mutation-detectable:
//   1. `finalPath` is never reassigned — the caller's destination is the destination.
//   2. the scratch file is derived from `finalPath`, not from the canonical name, so a nightly dump
//      and a safety dump running into the same directory cannot share it.
func TestDumpOneToHonoursTheDestinationItWasGiven(t *testing.T) {
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "dbdump.go", nil, 0)
	if err != nil {
		t.Fatal(err)
	}
	var body *ast.BlockStmt
	for _, d := range f.Decls {
		if fn, ok := d.(*ast.FuncDecl); ok && fn.Name.Name == "DumpOneTo" && fn.Body != nil {
			body = fn.Body
		}
	}
	if body == nil {
		t.Fatal("DumpOneTo not found — this guard can no longer prove anything")
	}

	// 1. no assignment to finalPath
	ast.Inspect(body, func(n ast.Node) bool {
		as, ok := n.(*ast.AssignStmt)
		if !ok {
			return true
		}
		for _, lhs := range as.Lhs {
			if id, ok := lhs.(*ast.Ident); ok && id.Name == "finalPath" {
				t.Errorf("DumpOneTo REASSIGNS finalPath at line %d — the caller's destination must be "+
					"the destination. This is R-361: the safety dump asked for its own name and got the "+
					"app's canonical dump written instead, destroying the app's only database backup.",
					fset.Position(as.Pos()).Line)
			}
		}
		return true
	})

	// 2. tmpPath is built from finalPath
	var tmpFromFinal bool
	ast.Inspect(body, func(n ast.Node) bool {
		as, ok := n.(*ast.AssignStmt)
		if !ok || len(as.Lhs) != 1 || len(as.Rhs) != 1 {
			return true
		}
		id, ok := as.Lhs[0].(*ast.Ident)
		if !ok || id.Name != "tmpPath" {
			return true
		}
		bin, ok := as.Rhs[0].(*ast.BinaryExpr)
		if ok {
			if x, ok := bin.X.(*ast.Ident); ok && x.Name == "finalPath" {
				tmpFromFinal = true
			}
		}
		return true
	})
	if !tmpFromFinal {
		t.Error("tmpPath is not derived from finalPath — two dumps into the same directory could share " +
			"a scratch file, which is the same collision R-361 is about, one file over")
	}
}