package main

import (
	"bytes"
	"context"
	"database/sql"
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"syscall"
	"testing"
	"time"

	"textmachine/backend/internal/pipeline"
	"textmachine/backend/internal/store"
)

// migrate_cli_test.go is the CLI half of backlog row 174: the deploy deadlock is a SHELL fact — the
// platform learns what happened from an exit code and a line of stderr — so the contract is exercised
// where it is a contract. The migration mechanics themselves are pinned generically in
// internal/store/migrate_test.go.

// staleTheProjectSchema rolls the project database's recorded version back one step, which is what an
// older engine binary left behind.
//
// ⚠ This fixture re-applies the newest migration on the next write open, which is fine while that step
// is `CREATE … IF NOT EXISTS` and is NOT guaranteed for a future ALTER step (backlog row 49а). It is
// used here because these tests are about the exit codes and the output, and the deep fixture — the
// migration chain truncated to an older vintage — is only reachable from inside the store package,
// where those properties are tested. If a future migration makes this fail, move the setup rather than
// weakening the assertions.
func staleTheProjectSchema(t *testing.T, dbPath string) int {
	t.Helper()
	db, err := sql.Open("sqlite", "file:"+dbPath)
	if err != nil {
		t.Fatal(err)
	}
	defer db.Close()
	if _, err := db.Exec(`DELETE FROM schema_version WHERE version = (SELECT MAX(version) FROM schema_version)`); err != nil {
		t.Fatal(err)
	}
	return schemaVersionOf(t, dbPath)
}

// schemaVersionOf reads the recorded schema version through its own connection — the state under test
// must be asserted independently of the product code that reports it.
func schemaVersionOf(t *testing.T, dbPath string) int {
	t.Helper()
	db, err := sql.Open("sqlite", "file:"+dbPath)
	if err != nil {
		t.Fatal(err)
	}
	defer db.Close()
	var v int
	if err := db.QueryRow(`SELECT COALESCE(MAX(version), 0) FROM schema_version`).Scan(&v); err != nil {
		t.Fatal(err)
	}
	return v
}

// holdTheProject takes the project's exclusive flock the way another tmctl process would, WITHOUT
// opening the store — because a write open would migrate the database, and the state under test is a
// project that is both stale and held.
func holdTheProject(t *testing.T, dbPath string) {
	t.Helper()
	f, err := os.OpenFile(dbPath+".lock", os.O_CREATE|os.O_RDWR, 0o644)
	if err != nil {
		t.Fatal(err)
	}
	if err := syscall.Flock(int(f.Fd()), syscall.LOCK_EX|syscall.LOCK_NB); err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() {
		_ = syscall.Flock(int(f.Fd()), syscall.LOCK_UN)
		f.Close()
	})
}

func projectDBOf(bookPath string) string {
	return filepath.Join(filepath.Dir(bookPath), "cli-book.db")
}

func backupsOf(t *testing.T, dbPath string) []string {
	t.Helper()
	entries, err := os.ReadDir(backupDirFor(dbPath))
	if os.IsNotExist(err) {
		return nil
	}
	if err != nil {
		t.Fatal(err)
	}
	var names []string
	for _, e := range entries {
		names = append(names, e.Name())
	}
	return names
}

// mockProvider answers every call with a usable draft, so a `translate` really settles money.
func mockProvider(t *testing.T) *httptest.Server {
	t.Helper()
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		_, _ = io.ReadAll(r.Body)
		fmt.Fprint(w, `{"id":"fake","model":"fake-model","choices":[{"message":{"content":"ЧЕРНОВИК ПЕРЕВОДА"},"finish_reason":"stop"}],
			"usage":{"prompt_tokens":1000,"completion_tokens":500}}`)
	}))
	t.Cleanup(srv.Close)
	return srv
}

// TestTheDeployDeadlockIsBrokenAtTheShell drives the real binary through the exact sequence the
// platform meets on an engine upgrade: `status --json` before a spawn refuses the older schema, and the
// contract must make that refusal actionable — its own number inside the refusal band, and the two
// versions machine-readable — so the caller can migrate and start the run instead of stopping the world.
func TestTheDeployDeadlockIsBrokenAtTheShell(t *testing.T) {
	if testing.Short() {
		t.Skip("builds and runs the binary")
	}
	bin := buildTmctl(t)
	bookPath := setupCLIProject(t, mockProvider(t).URL)
	dbPath := projectDBOf(bookPath)

	// A book an older binary left behind.
	st, err := store.Open(dbPath)
	if err != nil {
		t.Fatal(err)
	}
	st.Close()
	from := staleTheProjectSchema(t, dbPath)

	var stderr bytes.Buffer
	status := exec.Command(bin, "status", "--config", bookPath, "--json")
	status.Stderr = &stderr
	if got := exitCodeOf(t, status.Run()); got != exitSchemaMismatch {
		t.Fatalf("`status --json` on an older schema exited %d, want %d", got, exitSchemaMismatch)
	}
	// The number says WHAT; these two say which way and how far — without them a caller cannot tell the
	// direction a migration repairs from the one where it would loop forever.
	want := fmt.Sprintf("schema_mismatch found=%d expected=%d", from, store.SchemaHead())
	if !strings.Contains(stderr.String(), want) {
		t.Fatalf("the refusal must carry %q machine-readably; got:\n%s", want, stderr.String())
	}
	if exitSchemaMismatch < refusalFirst || exitSchemaMismatch > refusalLast {
		t.Fatalf("%d is outside the refusal band [%d,%d] every consumer keys on", exitSchemaMismatch, refusalFirst, refusalLast)
	}

	out, err := exec.Command(bin, "migrate", "--config", bookPath).Output()
	if got := exitCodeOf(t, err); got != 0 {
		t.Fatalf("`migrate` exited %d: %s", got, out)
	}
	if want := fmt.Sprintf("schema v%d -> v%d", from, store.SchemaHead()); !strings.Contains(string(out), want) {
		t.Fatalf("migrate must report the transition %q; got:\n%s", want, out)
	}
	if got := exitCodeOf(t, exec.Command(bin, "status", "--config", bookPath, "--json").Run()); got != 0 {
		t.Fatalf("`status --json` after the migration exited %d, want 0 — the deadlock is not broken", got)
	}
	// …and the run the migration unblocked actually starts. It follows within milliseconds, which is
	// what put migrate's restore point and the paid path's pre-flight guard in the same second.
	if run := exec.Command(bin, "translate", "--config", bookPath); exitCodeOf(t, run.Run()) != 0 {
		t.Fatal("the run spawned right after the migration must start, not die in its pre-flight guard")
	}
}

// TestTheMigrationRestorePointNeverCollidesWithThePaidPath is the deterministic half of the same fact:
// both producers are handed the SAME stamp, because in the deploy sequence they really do land in the
// same second. `store.BackupSQLite` refuses to overwrite a restore point (backlog row 173), so sharing
// the name would make the run refuse to start with exit 1 — outside the refusal band, and after a
// migration that already succeeded.
func TestTheMigrationRestorePointNeverCollidesWithThePaidPath(t *testing.T) {
	bookPath := setupCLIProject(t, "http://127.0.0.1:1")
	dbPath := projectDBOf(bookPath)
	st, err := store.Open(dbPath)
	if err != nil {
		t.Fatal(err)
	}
	st.Close()
	staleTheProjectSchema(t, dbPath)

	// PRODUCTION takes the restore point — the point of the test. Supplying the name here instead would
	// only pin that the constant is non-empty, and the regression to catch is the call site dropping it.
	if err := migrateCmd(bookPath, io.Discard); err != nil {
		t.Fatal(err)
	}
	names := backupsOf(t, dbPath)
	if len(names) != 1 {
		t.Fatalf("restore points after the migration: %v, want exactly one", names)
	}

	// Strip the tag production chose and the bare second-stamp must still be free, so translate's
	// pre-flight guard can take its own backup in the SAME second. Untagged, the two names are equal and
	// BackupSQLite refuses to overwrite — the run the migration just unblocked would die in its
	// pre-flight guard with exit 1. No wall clock is involved: the collision is decided by the name.
	tagged := strings.TrimSuffix(names[0], ".db")
	bare := strings.TrimSuffix(tagged, migrateSuffix)
	if bare == tagged {
		t.Fatalf("the migration's restore point %q carries no tag of its own — it is inside the paid path's namespace", names[0])
	}
	if _, err := store.BackupSQLite(dbPath, backupDirFor(dbPath), bare); err != nil {
		t.Fatalf("the paid path's pre-flight backup in the SAME second must still succeed: %v", err)
	}
}

// TestMigrateNeedsNeitherPricesNorModels: the $0 path must not carry the paid path's gates. A
// models.yaml whose prices are older than 120 days refuses to load (backlog row 146), and if the
// migration were built on the full config stack a stand with stale prices would meet the same deadlock
// this command exists to remove — the read command refuses, and the one thing that could migrate
// refuses too.
func TestMigrateNeedsNeitherPricesNorModels(t *testing.T) {
	bookPath := setupCLIProject(t, mockProvider(t).URL)
	modelsPath := filepath.Join(filepath.Dir(bookPath), "models.yaml")
	raw, err := os.ReadFile(modelsPath)
	if err != nil {
		t.Fatal(err)
	}
	stale := time.Now().UTC().AddDate(0, 0, -200).Format("2006-01-02")
	writeCLIFile(t, modelsPath, strings.Replace(string(raw), time.Now().UTC().Format("2006-01-02"), stale, 1))

	// The contrast: the read-only projection is refused by the price gate before it reads a schema.
	if got := exitCode(status(context.Background(), bookPath, true)); got != exitConfigInvalid {
		t.Fatalf("setup: `status` on stale prices exited %d, want %d", got, exitConfigInvalid)
	}
	var out bytes.Buffer
	if err := migrateCmd(bookPath, &out); err != nil {
		t.Fatalf("migrate must not consult prices: %v", err)
	}
	if !strings.Contains(out.String(), fmt.Sprintf("v%d", store.SchemaHead())) {
		t.Fatalf("migrate must report the head it brought the project to; got %q", out.String())
	}

	// The structural version of the same claim, which also covers the provider keys the models file
	// carries: with no models.yaml at all the migration still runs, so it cannot be consulting either.
	if err := os.Remove(modelsPath); err != nil {
		t.Fatal(err)
	}
	if got := exitCode(status(context.Background(), bookPath, true)); got != exitConfigInvalid {
		t.Fatalf("setup: `status` without models.yaml exited %d, want %d", got, exitConfigInvalid)
	}
	if err := migrateCmd(bookPath, io.Discard); err != nil {
		t.Fatalf("migrate must not load the model stack at all: %v", err)
	}
}

// TestMigrateKeepsTheMoneyAndRepeatsAsANoOp is the money half at the command level: a real run's
// settled spend, a reservation its process never settled, and a migration between them. `committed` is
// what the platform's ceiling argument is computed from (PD-158) and what a settle reconciles against,
// so it must survive the deploy step untouched; `reserved` is advisory and the write open's recovery
// pass is entitled to zero it.
func TestMigrateKeepsTheMoneyAndRepeatsAsANoOp(t *testing.T) {
	bookPath := setupCLIProject(t, mockProvider(t).URL)
	dbPath := projectDBOf(bookPath)
	if err := translate(context.Background(), bookPath, false, pipeline.RebillConsent{}, false, 0, 0); err != nil {
		t.Fatalf("setup run: %v", err)
	}

	st, err := store.Open(dbPath)
	if err != nil {
		t.Fatal(err)
	}
	committed, _, err := st.SpentUSD("cli-book")
	if err != nil {
		t.Fatal(err)
	}
	if committed <= 0 {
		t.Fatalf("setup: the run must have settled money, committed=%v", committed)
	}
	// The reservation a killed run leaves behind.
	if _, verdict, err := st.Reserve("cli-book", 0.25, store.Ceilings{BookUSD: 10, DayUSD: 10}); err != nil || verdict != store.ReserveOK {
		t.Fatalf("stale reserve: %v %v", verdict, err)
	}
	st.Close()
	from := staleTheProjectSchema(t, dbPath)

	for i := range 2 {
		var out bytes.Buffer
		if err := migrateCmd(bookPath, &out); err != nil {
			t.Fatalf("call %d: %v", i, err)
		}
		ro, err := store.OpenReadOnly(dbPath)
		if err != nil {
			t.Fatalf("call %d: the read path must work after migrating: %v", i, err)
		}
		gotCommitted, gotReserved, err := ro.SpentUSD("cli-book")
		ro.Close()
		if err != nil {
			t.Fatal(err)
		}
		if gotCommitted != committed {
			t.Fatalf("call %d: committed %v -> %v; a migration must not move settled money by a cent", i, committed, gotCommitted)
		}
		if gotReserved != 0 {
			t.Fatalf("call %d: reserved=%v, want the recovery pass to have zeroed it", i, gotReserved)
		}
		// The restore point is taken for the call that MIGRATES and for no other, and it holds the
		// database as it was BEFORE the step — a copy taken afterwards is not a restore point at all.
		names := backupsOf(t, dbPath)
		if len(names) != 1 {
			t.Fatalf("call %d: restore points %v, want exactly the one the migrating call took", i, names)
		}
		if v := schemaVersionOf(t, filepath.Join(backupDirFor(dbPath), names[0])); v != from {
			t.Fatalf("call %d: the restore point is at schema v%d, want the pre-migration v%d", i, v, from)
		}
		if i == 1 && !strings.Contains(out.String(), "already at schema") {
			t.Fatalf("the repeat call must report a no-op; got %q", out.String())
		}
	}
}

func TestMigrateRefusesWithTheSameVocabularyAsEveryOtherCommand(t *testing.T) {
	t.Run("a broken config", func(t *testing.T) {
		bookPath := setupCLIProject(t, "http://127.0.0.1:1")
		writeCLIFile(t, bookPath, "book_id: cli-book\n  bad indentation: [\n")
		if got := exitCode(migrateCmd(bookPath, io.Discard)); got != exitConfigInvalid {
			t.Fatalf("exit %d, want %d", got, exitConfigInvalid)
		}
	})

	t.Run("a project another process holds", func(t *testing.T) {
		// The deploy step runs while the operator believes the runs are stopped. If one is not, the
		// answer is "come back later" — never a migration under a live writer's feet, whose reservations
		// the recovery pass would zero. And nothing may be written for that refusal: a restore point
		// taken before the lock would copy the whole database once per retry.
		bookPath := setupCLIProject(t, "http://127.0.0.1:1")
		dbPath := projectDBOf(bookPath)
		st, err := store.Open(dbPath)
		if err != nil {
			t.Fatal(err)
		}
		st.Close()
		staleTheProjectSchema(t, dbPath)
		holdTheProject(t, dbPath)

		if got := exitCode(migrateCmd(bookPath, io.Discard)); got != exitProjectLocked {
			t.Fatalf("exit %d, want %d", got, exitProjectLocked)
		}
		if got := backupsOf(t, dbPath); len(got) != 0 {
			t.Fatalf("a refused migration wrote %v; nothing may be written for a project it does not own", got)
		}
		// The retry the refusal invites reaches the lock too, instead of dying on the leftovers of the
		// previous attempt.
		if got := exitCode(migrateCmd(bookPath, io.Discard)); got != exitProjectLocked {
			t.Fatalf("retry exited %d, want %d again", got, exitProjectLocked)
		}
	})

	t.Run("a project newer than this binary", func(t *testing.T) {
		// The direction a migration cannot repair. It must not read as success, or a caller looping
		// "status refused → migrate → retry" would loop forever on a rolled-back binary.
		bookPath := setupCLIProject(t, "http://127.0.0.1:1")
		dbPath := projectDBOf(bookPath)
		st, err := store.Open(dbPath)
		if err != nil {
			t.Fatal(err)
		}
		st.Close()
		db, err := sql.Open("sqlite", "file:"+dbPath)
		if err != nil {
			t.Fatal(err)
		}
		if _, err := db.Exec(`INSERT INTO schema_version (version) VALUES (?)`, store.SchemaHead()+7); err != nil {
			t.Fatal(err)
		}
		db.Close()
		err = migrateCmd(bookPath, io.Discard)
		if got := exitCode(err); got != exitSchemaMismatch {
			t.Fatalf("exit %d, want %d", got, exitSchemaMismatch)
		}
		if !strings.Contains(err.Error(), fmt.Sprintf("schema_mismatch found=%d expected=%d", store.SchemaHead()+7, store.SchemaHead())) {
			t.Fatalf("the refusal must name both versions machine-readably: %v", err)
		}
		if got := backupsOf(t, dbPath); len(got) != 0 {
			t.Fatalf("a refused migration wrote %v", got)
		}
	})

	t.Run("a book that has never been run", func(t *testing.T) {
		// The deploy sweep does not have to know which books have a database yet. Nothing is backed up:
		// a database this call creates has no history to lose.
		bookPath := setupCLIProject(t, "http://127.0.0.1:1")
		var out bytes.Buffer
		if err := migrateCmd(bookPath, &out); err != nil {
			t.Fatal(err)
		}
		if !strings.Contains(out.String(), "created") {
			t.Fatalf("migrate must say it created the project; got %q", out.String())
		}
		if v := schemaVersionOf(t, projectDBOf(bookPath)); v != store.SchemaHead() {
			t.Fatalf("created at v%d, want v%d", v, store.SchemaHead())
		}
		if got := backupsOf(t, projectDBOf(bookPath)); len(got) != 0 {
			t.Fatalf("a project being created was backed up: %v", got)
		}
	})
}