// SPDX-License-Identifier: GPL-3.0-or-later

package engine

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"reflect"
	"strings"
	"testing"
	"time"
)

const dlConf = `
(path "~/dl")
(recursive yes)
(min-age 0s)
(ignore "*.part")
(rule "dups" (when (duplicate)) (move "Dupes") (stop))
(rule "acme" (when (type document) (content "acme ltd")) (move "Work/Acme") (stop))
(rule "images" (when (type image)) (move "Pictures"))
(rule "rest" (when (not (matched)) (type text)) (move "Other"))
`

// fixture builds ~/dl and returns a loaded engine. PATH is empty, so no
// extraction tool exists and PDFs and .doc files are unreadable.
func fixture(t *testing.T) (*Engine, *Dir, string) {
	t.Helper()
	h := sandbox(t)
	t.Setenv("PATH", t.TempDir())
	dl := filepath.Join(h, "dl")
	files := map[string]string{
		"inv1.txt":            "Invoice from ACME LTD, tax 0000000000",
		"notes.txt":           "shopping list",
		"photo.jpg":           "\xff\xd8\xff\xe0 jpeg bytes",
		"report.pdf":          "%PDF same bytes",
		"report (1).pdf":      "%PDF same bytes",
		"brochure.doc":        "\xd0\xcf\x11\xe0 doc bytes",
		"movie.mkv":           "video",
		"movie.mkv.part":      "partial",
		"Work/Acme/filed.txt": "acme ltd, already filed",
		"Pictures/old.jpg":    "\xff\xd8 old",
	}
	old := time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC)
	for name, body := range files {
		p := filepath.Join(dl, name)
		os.MkdirAll(filepath.Dir(p), 0o755)
		if err := os.WriteFile(p, []byte(body), 0o644); err != nil {
			t.Fatal(err)
		}
		os.Chtimes(p, old, old)
	}
	newer := old.Add(time.Hour)
	os.Chtimes(filepath.Join(dl, "report (1).pdf"), newer, newer)
	main := writeConfig(t, h, `(include "dl")`, map[string]string{"dl": dlConf})
	e, errs := Load(main)
	if len(errs) > 0 {
		t.Fatal(errs)
	}
	return e, e.Dirs[0], dl
}

// summary renders a result compactly for comparison.
func summary(r *Result) []string {
	var out []string
	for _, m := range r.Matched {
		var rs []string
		for _, rm := range m.Rules {
			rs = append(rs, rm.Rule.Name+"["+strings.Join(rm.Reasons, "; ")+"]")
		}
		out = append(out, "match "+m.File.Rel+" "+strings.Join(rs, " "))
	}
	for _, m := range r.Unmatched {
		out = append(out, "none "+m.File.Rel+" "+strings.Join(m.Warnings, " | "))
	}
	for _, s := range r.Skipped {
		out = append(out, "skip "+s.Rel+" "+s.Reason.String())
	}
	return out
}

func TestMatch(t *testing.T) {
	e, d, _ := fixture(t)
	r, err := e.Match(context.Background(), d)
	if err != nil {
		t.Fatal(err)
	}
	want := []string{
		`match inv1.txt acme[type txt; content "acme ltd"]`,
		`match notes.txt rest[not matched; type txt]`,
		`match photo.jpg images[type jpg]`,
		`match report (1).pdf dups[duplicate of report.pdf]`,
		`none brochure.doc acme: content unreadable: needs antiword or catdoc, not installed`,
		`none report.pdf acme: content unreadable: needs pdftotext, not installed`,
		`skip movie.mkv busy`,
		`skip movie.mkv.part ignored`,
	}
	if got := summary(r); !reflect.DeepEqual(got, want) {
		t.Fatalf("got\n%s\nwant\n%s", strings.Join(got, "\n"), strings.Join(want, "\n"))
	}
	again, _ := e.Match(context.Background(), d)
	if !reflect.DeepEqual(summary(again), summary(r)) {
		t.Fatal("a second run gave a different result")
	}
}

func TestMatchMissingRoot(t *testing.T) {
	e, d, dl := fixture(t)
	os.RemoveAll(dl)
	if _, err := e.Match(context.Background(), d); err == nil {
		t.Fatal("no error for a missing root")
	}
}

func TestExplain(t *testing.T) {
	e, _, dl := fixture(t)
	x, err := e.Explain(context.Background(), filepath.Join(dl, "inv1.txt"))
	if err != nil {
		t.Fatal(err)
	}
	var got []string
	for _, rt := range x.Rules {
		got = append(got, fmt.Sprintf("%s match=%v stopped=%q trace=%v", rt.Rule.Name, rt.Match, rt.Stopped, rt.Trace != nil))
	}
	want := []string{
		`dups match=false stopped="" trace=true`,
		`acme match=true stopped="" trace=true`,
		`images match=false stopped="stopped by rule acme" trace=false`,
		`rest match=false stopped="stopped by rule acme" trace=false`,
	}
	if !reflect.DeepEqual(got, want) || x.Skip != "" {
		t.Fatalf("skip=%q\n%s", x.Skip, strings.Join(got, "\n"))
	}
	for name, skip := range map[string]string{
		"movie.mkv":           "busy",
		"movie.mkv.part":      "ignored",
		"Work/Acme/filed.txt": "inside a rule destination, which krino never scans",
	} {
		x, err := e.Explain(context.Background(), filepath.Join(dl, name))
		if err != nil || x.Skip != skip {
			t.Errorf("%s: skip %q, %v; want %q", name, x.Skip, err, skip)
		}
	}
	if _, err := e.Explain(context.Background(), "/etc/hostname"); err == nil || !strings.HasSuffix(err.Error(), "is not inside any included directory") {
		t.Errorf("outside: %v", err)
	}
}

// TestMatchExcludesOnlyRuleDest checks that a rule destination with no
// placeholder excludes exactly that directory, not its parent: a sibling
// subdirectory of the destination's parent must still be scanned.
func TestMatchExcludesOnlyRuleDest(t *testing.T) {
	h := sandbox(t)
	dl := filepath.Join(h, "dl")
	files := map[string]string{
		"Work/Acme/filed.txt": "already filed",
		"Work/Other/keep.txt": "keep me",
	}
	for name, body := range files {
		p := filepath.Join(dl, name)
		if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(p, []byte(body), 0o644); err != nil {
			t.Fatal(err)
		}
	}
	conf := `
(path "~/dl")
(recursive yes)
(min-age 0s)
(rule "acme" (when (name "nope")) (move "Work/Acme"))
`
	main := writeConfig(t, h, `(include "dl")`, map[string]string{"dl": conf})
	e, errs := Load(main)
	if len(errs) > 0 {
		t.Fatal(errs)
	}
	r, err := e.Match(context.Background(), e.Dirs[0])
	if err != nil {
		t.Fatal(err)
	}
	seen := map[string]bool{}
	for _, m := range r.Matched {
		seen[m.File.Rel] = true
	}
	for _, m := range r.Unmatched {
		seen[m.File.Rel] = true
	}
	for _, s := range r.Skipped {
		seen[s.Rel] = true
	}
	if !seen["Work/Other/keep.txt"] {
		t.Error("Work/Other/keep.txt should have been scanned: only the rule's own destination (Work/Acme) may be excluded")
	}
	if seen["Work/Acme/filed.txt"] {
		t.Error("Work/Acme/filed.txt should have been excluded as inside the rule's destination")
	}
}

// TestMatchWarningsSorted checks that Result.Warnings is sorted, not in
// whatever order concurrent workers happened to build the duplicate
// indexes that failed: rule "b" (declared first, with a stop that must
// not skip rule "a" since it never matches) names a missing directory
// that sorts after rule "a"'s, and rule "c" names the very same missing
// directory as rule "a" - which must fold into one warning, not two.
func TestMatchWarningsSorted(t *testing.T) {
	h := sandbox(t)
	dl := filepath.Join(h, "dl")
	if err := os.MkdirAll(dl, 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(dl, "only.txt"), []byte("hello"), 0o644); err != nil {
		t.Fatal(err)
	}
	conf := `
(path "~/dl")
(recursive yes)
(min-age 0s)
(rule "b" (when (duplicate "~/zz-missing")) (stop))
(rule "a" (when (duplicate "~/aa-missing")) (stop))
(rule "c" (when (duplicate "~/aa-missing")) (stop))
`
	main := writeConfig(t, h, `(include "dl")`, map[string]string{"dl": conf})
	e, errs := Load(main)
	if len(errs) > 0 {
		t.Fatal(errs)
	}
	r, err := e.Match(context.Background(), e.Dirs[0])
	if err != nil {
		t.Fatal(err)
	}
	if len(r.Warnings) != 2 {
		t.Fatalf("got %d warnings, want 2 (the shared aa-missing dir should fold into one):\n%s", len(r.Warnings), strings.Join(r.Warnings, "\n"))
	}
	wantPrefix := []string{"duplicate: ~/aa-missing:", "duplicate: ~/zz-missing:"}
	for i, want := range wantPrefix {
		if !strings.HasPrefix(r.Warnings[i], want) {
			t.Errorf("Warnings[%d] = %q, want prefix %q", i, r.Warnings[i], want)
		}
	}
}

// TestExcludeDirs is a table check of excludeDirs's rule-destination
// handling, in rule order: a plain destination excludes itself exactly; a
// destination with a placeholder excludes only the static part before it,
// cut back to a full path component; a destination (after that cut) equal
// to the root itself, or outside the root, excludes nothing; an absolute
// destination inside the root excludes that directory; copy counts like
// move; rename is not a destination at all.
func TestExcludeDirs(t *testing.T) {
	h := sandbox(t)
	root := filepath.Join(h, "root")
	absDest := filepath.Join(root, "AbsDest")
	conf := `
(path "` + root + `")
(rule "r1" (move "Work/Acme"))
(rule "r2" (move "Photos/{mtime:%Y}"))
(rule "r3" (move "Work/Acme-{mtime:%Y}"))
(rule "r4" (move "{ext}"))
(rule "r5" (move "."))
(rule "r6" (move "~/elsewhere"))
(rule "r7" (move "` + absDest + `"))
(rule "r8" (copy "Backup"))
(rule "r9" (rename "x-{name}"))
(rule "r10" (move "Lit/{{a}}/{mtime:%Y}"))
`
	main := writeConfig(t, h, `(include "dl")`, map[string]string{"dl": conf})
	e, errs := Load(main)
	if len(errs) > 0 {
		t.Fatal(errs)
	}
	got := e.excludeDirs(e.Dirs[0])
	want := []string{
		filepath.Join(root, "Work", "Acme"), // r1: no placeholder, exact
		filepath.Join(root, "Photos"),       // r2: cut back to "Photos/"
		filepath.Join(root, "Work"),         // r3: cut back past "Acme-"
		// r4 "{ext}": nothing before "{" at all -> resolves to the root
		// itself -> not strictly inside it -> excludes nothing.
		// r5 ".": no placeholder, resolves to the root itself -> nothing.
		// r6 "~/elsewhere": outside the root -> nothing.
		absDest,                       // r7: absolute, already inside root
		filepath.Join(root, "Backup"), // r8: copy counts like move
		// r9 rename "x-{name}": rename is never a destination.
		filepath.Join(root, "Lit", "{a}"), // r10: "{{a}}" is literal text
	}
	if !reflect.DeepEqual(got, want) {
		t.Fatalf("excludeDirs =\n%v\nwant\n%v", got, want)
	}
}

// TestMatchDrainsDupCandidateErrors: A1 plumbing across the dup/engine
// boundary. Within one directory's own scan (no extra directories), a
// candidate that cannot be hashed must not poison the duplicate answer for
// its size-mates, and must surface exactly once in Result.Warnings, its
// path abbreviated the way every other user-visible path is.
func TestMatchDrainsDupCandidateErrors(t *testing.T) {
	if os.Geteuid() == 0 {
		t.Skip("permissions are not enforced running as root")
	}
	h := sandbox(t)
	dl := filepath.Join(h, "dl")
	old := time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC)
	files := map[string]string{
		"a.txt": "same content", // older: the original
		"b.txt": "same content", // newer: reported as the duplicate
		"c.txt": "diff content", // same size as a/b, different bytes
	}
	for name, body := range files {
		p := filepath.Join(dl, name)
		if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(p, []byte(body), 0o644); err != nil {
			t.Fatal(err)
		}
	}
	os.Chtimes(filepath.Join(dl, "a.txt"), old, old)
	os.Chtimes(filepath.Join(dl, "b.txt"), old.Add(time.Hour), old.Add(time.Hour))
	os.Chtimes(filepath.Join(dl, "c.txt"), old, old)
	cPath := filepath.Join(dl, "c.txt")
	if err := os.Chmod(cPath, 0o000); err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { os.Chmod(cPath, 0o644) })

	conf := `
(path "~/dl")
(recursive yes)
(min-age 0s)
(rule "dup" (when (duplicate)) (stop))
`
	main := writeConfig(t, h, `(include "dl")`, map[string]string{"dl": conf})
	e, errs := Load(main)
	if len(errs) > 0 {
		t.Fatal(errs)
	}
	r, err := e.Match(context.Background(), e.Dirs[0])
	if err != nil {
		t.Fatal(err)
	}

	var bReasons []string
	for _, m := range r.Matched {
		if m.File.Rel == "b.txt" {
			for _, rm := range m.Rules {
				bReasons = append(bReasons, rm.Reasons...)
			}
		}
	}
	if len(bReasons) == 0 || bReasons[0] != "duplicate of a.txt" {
		t.Errorf("b.txt duplicate pair with a.txt broken by unreadable sibling c.txt: %v", summary(r))
	}

	want := "duplicate: ~/dl/c.txt: "
	found := 0
	for _, w := range r.Warnings {
		if strings.HasPrefix(w, want) {
			found++
		}
	}
	if found != 1 {
		t.Errorf("got %d warnings with prefix %q, want 1; warnings: %v", found, want, r.Warnings)
	}
}

// TestDuplicateWarningsShareOneFormat: a missing extra directory and a
// candidate that cannot be hashed are both reported as "duplicate: PATH:
// cause", the path abbreviated and not repeated raw inside the cause
// (triage 6).
func TestDuplicateWarningsShareOneFormat(t *testing.T) {
	if os.Getuid() == 0 {
		t.Skip("root reads a chmod 000 file")
	}
	h := sandbox(t)
	dl := filepath.Join(h, "dl")
	extra := filepath.Join(h, "extra")
	os.MkdirAll(dl, 0o755)
	os.MkdirAll(extra, 0o755)
	old := time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC)
	for _, p := range []string{filepath.Join(dl, "a.txt"), filepath.Join(extra, "c.txt")} {
		os.WriteFile(p, []byte("same size"), 0o644)
		os.Chtimes(p, old, old)
	}
	os.Chmod(filepath.Join(extra, "c.txt"), 0)
	t.Cleanup(func() { os.Chmod(filepath.Join(extra, "c.txt"), 0o644) })
	main := writeConfig(t, h, `(include "dl")`, map[string]string{"dl": `
(path "~/dl")
(rule "d" (when (duplicate "~/extra" "~/nonexistent")) (move "Dupes"))
`})
	e, errs := Load(main)
	if len(errs) > 0 {
		t.Fatal(errs)
	}
	r, err := e.Match(context.Background(), e.Dirs[0])
	if err != nil {
		t.Fatal(err)
	}
	want := map[string]bool{
		"duplicate: ~/extra/c.txt: open: permission denied":          false,
		"duplicate: ~/nonexistent: lstat: no such file or directory": false,
	}
	for _, w := range r.Warnings {
		if strings.Contains(w, h) {
			t.Errorf("warning repeats the raw path: %q", w)
		}
		if _, ok := want[w]; ok {
			want[w] = true
		}
	}
	for w, seen := range want {
		if !seen {
			t.Errorf("missing warning %q in %q", w, r.Warnings)
		}
	}
}