package memory

import (
	"bufio"
	"encoding/json"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"local-review-harness/internal/analyzers"
)

// === Gate E1 — append-only contract ===
//
// PROMPT.md hard rule: "Memory should be append-only by default.
// Never silently overwrite prior memory." Every Writer.Append* must
// open with O_APPEND, never O_TRUNC. Truncation is the failure mode
// this package exists to prevent — operators relying on .memory/ to
// see drift across runs would silently lose history.
//
// This test does the receipt-honesty equivalent: write once, write
// again with different content, assert the FIRST write's content is
// still visible in the file.

func TestAppendKnownRisks_NeverTruncates(t *testing.T) {
	repo := t.TempDir()
	w, err := NewWriter(repo)
	if err != nil {
		t.Fatal(err)
	}

	// Run 1: write 2 findings
	run1 := []analyzers.Finding{
		{ID: "abc111", Title: "first run finding 1", File: "a.go", Severity: analyzers.SeverityHigh},
		{ID: "abc222", Title: "first run finding 2", File: "b.go", Severity: analyzers.SeverityMedium},
	}
	if err := w.AppendKnownRisks("run-1", run1); err != nil {
		t.Fatal(err)
	}

	// Run 2: write 1 different finding
	run2 := []analyzers.Finding{
		{ID: "def333", Title: "second run finding", File: "c.go", Severity: analyzers.SeverityCritical},
	}
	if err := w.AppendKnownRisks("run-2", run2); err != nil {
		t.Fatal(err)
	}

	// Read back: file should contain ALL 3 entries (2+1), not just run 2's.
	entries := readAll(t, filepath.Join(repo, ".memory", "known-risks.jsonl"))
	if len(entries) != 3 {
		t.Fatalf("expected 3 entries (2 from run 1 + 1 from run 2); got %d", len(entries))
	}
	if !strings.Contains(entries[0], "abc111") || !strings.Contains(entries[0], "run-1") {
		t.Errorf("first entry should be run 1's first finding; got %q", entries[0])
	}
	if !strings.Contains(entries[2], "def333") || !strings.Contains(entries[2], "run-2") {
		t.Errorf("last entry should be run 2's finding; got %q", entries[2])
	}
}

func TestAppendRunHistory_NeverTruncates(t *testing.T) {
	repo := t.TempDir()
	w, _ := NewWriter(repo)

	for i, r := range []RunHistoryEntry{
		{RunID: "run-A", RepoPath: repo, TotalFindings: 5},
		{RunID: "run-B", RepoPath: repo, TotalFindings: 8},
		{RunID: "run-C", RepoPath: repo, TotalFindings: 3},
	} {
		if err := w.AppendRunHistory(r); err != nil {
			t.Fatalf("append %d: %v", i, err)
		}
	}

	entries := readAll(t, filepath.Join(repo, ".memory", "run-history.jsonl"))
	if len(entries) != 3 {
		t.Fatalf("expected 3 history entries; got %d", len(entries))
	}
	for i, expected := range []string{"run-A", "run-B", "run-C"} {
		var entry RunHistoryEntry
		if err := json.Unmarshal([]byte(entries[i]), &entry); err != nil {
			t.Fatalf("entry %d: %v", i, err)
		}
		if entry.RunID != expected {
			t.Errorf("entry %d: RunID = %q, want %q", i, entry.RunID, expected)
		}
	}
}

func TestAppendKnownRisks_EmptyFindingsIsNoop(t *testing.T) {
	// Calling Append with zero findings shouldn't even create the file —
	// avoids polluting .memory/ with empty files on clean runs.
	repo := t.TempDir()
	w, _ := NewWriter(repo)
	if err := w.AppendKnownRisks("run-empty", nil); err != nil {
		t.Fatal(err)
	}
	if _, err := os.Stat(filepath.Join(repo, ".memory", "known-risks.jsonl")); !os.IsNotExist(err) {
		t.Errorf("empty append should not create the file; stat err = %v", err)
	}
}

func TestWriteProjectProfile_OverwriteIsAllowed(t *testing.T) {
	// project-profile.json is the ONLY memory file allowed to overwrite —
	// it's a snapshot, not a log. Verify the overwrite semantic works.
	repo := t.TempDir()
	w, _ := NewWriter(repo)
	if err := w.WriteProjectProfile(ProjectProfile{
		RepoPath: repo, FileCount: 100,
	}); err != nil {
		t.Fatal(err)
	}
	if err := w.WriteProjectProfile(ProjectProfile{
		RepoPath: repo, FileCount: 200,
	}); err != nil {
		t.Fatal(err)
	}
	bs, err := os.ReadFile(filepath.Join(repo, ".memory", "project-profile.json"))
	if err != nil {
		t.Fatal(err)
	}
	var p ProjectProfile
	if err := json.Unmarshal(bs, &p); err != nil {
		t.Fatal(err)
	}
	if p.FileCount != 200 {
		t.Errorf("project-profile should reflect last write (200); got %d", p.FileCount)
	}
}

// readAll reads a JSONL file; returns one string per line.
func readAll(t *testing.T, path string) []string {
	t.Helper()
	f, err := os.Open(path)
	if err != nil {
		t.Fatalf("open %s: %v", path, err)
	}
	defer f.Close()
	var out []string
	s := bufio.NewScanner(f)
	for s.Scan() {
		out = append(out, s.Text())
	}
	return out
}