package store_test

import (
	"context"
	"database/sql"
	"os"
	"testing"

	"github.com/golang-migrate/migrate/v4"
	migratepgx "github.com/golang-migrate/migrate/v4/database/pgx/v5"
	"github.com/golang-migrate/migrate/v4/source/iofs"
	"github.com/stretchr/testify/require"

	_ "github.com/jackc/pgx/v5/stdlib" // register the "pgx" database/sql driver
)

// fileMigrator builds a golang-migrate instance from the on-disk migration files
// (not the embedded FS the production Migrate uses), so a test can step the schema
// up and down. os.DirFS(".") is rooted at the package dir; the SQL lives under
// "migrations". Mirrors store.Migrate's construction otherwise.
func fileMigrator(t *testing.T) *migrate.Migrate {
	t.Helper()
	db, err := sql.Open("pgx", dsn)
	require.NoError(t, err)
	t.Cleanup(func() { _ = db.Close() })

	drv, err := migratepgx.WithInstance(db, &migratepgx.Config{})
	require.NoError(t, err)
	src, err := iofs.New(os.DirFS("."), "migrations")
	require.NoError(t, err)
	m, err := migrate.NewWithInstance("iofs", src, "pgx", drv)
	require.NoError(t, err)
	t.Cleanup(func() { _, _ = m.Close() })
	return m
}

// loginEventsExists reports whether the login_events relation is present.
func loginEventsExists(t *testing.T) bool {
	t.Helper()
	var reg *string
	require.NoError(t, rawPool(t).QueryRow(context.Background(),
		`SELECT to_regclass('public.login_events')::text`).Scan(&reg))
	return reg != nil
}

// TestMigration010LoginEventsUpDown proves migration 010 is reversible: the down
// migration drops login_events cleanly and the up migration recreates it. A rotten
// down migration (forgotten DROP, dangling policy) would fail here rather than in
// production during a rollback. The test restores the schema to latest before
// returning so the shared embedded-postgres stays at HEAD for sibling tests.
func TestMigration010LoginEventsUpDown(t *testing.T) {
	newStore(t) // ensure the schema is migrated to latest (011 applied)
	require.True(t, loginEventsExists(t), "login_events must exist at latest migration")

	m := fileMigrator(t)
	// 011..016 sit above 010; step them down first so 010 is exercised in isolation.
	require.NoError(t, m.Steps(-1), "down 016 drops channel_caption_state, login_events intact")
	require.True(t, loginEventsExists(t), "016 down leaves login_events intact")
	require.NoError(t, m.Steps(-1), "down 015 reshapes transcripts, login_events intact")
	require.True(t, loginEventsExists(t), "015 down leaves login_events intact")
	require.NoError(t, m.Steps(-1), "down 014 drops channel_title, login_events intact")
	require.True(t, loginEventsExists(t), "014 down leaves login_events intact")
	require.NoError(t, m.Steps(-1), "down 013 drops channel_errors, login_events intact")
	require.True(t, loginEventsExists(t), "013 down leaves login_events intact")
	require.NoError(t, m.Steps(-1), "down 012 is a no-op, login_events intact")
	require.True(t, loginEventsExists(t), "012 down leaves login_events intact")
	require.NoError(t, m.Steps(-1), "down 011 must not touch login_events")
	require.True(t, loginEventsExists(t), "011 down leaves login_events intact")

	require.NoError(t, m.Steps(-1), "down 010 must drop login_events")
	require.False(t, loginEventsExists(t), "login_events must be gone after the down migration")

	require.NoError(t, m.Steps(7), "up must recreate 010 then re-apply 011..016")
	require.True(t, loginEventsExists(t), "login_events must be restored after the up migration")
}

// autoSummarizeDefault reads the users.auto_summarize column default as text
// ("true"/"false"), so the migration's default flip is verifiable directly.
func autoSummarizeDefault(t *testing.T) string {
	t.Helper()
	var def string
	require.NoError(t, rawPool(t).QueryRow(context.Background(),
		`SELECT column_default FROM information_schema.columns
		  WHERE table_name = 'users' AND column_name = 'auto_summarize'`).Scan(&def))
	return def
}

// TestMigration011AutoSummarizeDefaultUpDown proves migration 011 is reversible:
// up sets the auto_summarize column default to TRUE (ADR-018), down restores
// FALSE. The down intentionally does not revert existing rows — only the default.
func TestMigration011AutoSummarizeDefaultUpDown(t *testing.T) {
	newStore(t) // latest (013 applied)
	require.Equal(t, "true", autoSummarizeDefault(t), "011 sets the default to TRUE")

	m := fileMigrator(t)
	require.NoError(t, m.Steps(-1), "down 016 drops channel_caption_state")
	require.NoError(t, m.Steps(-1), "down 015 reshapes transcripts")
	require.NoError(t, m.Steps(-1), "down 014 drops channel_title")
	require.NoError(t, m.Steps(-1), "down 013 drops channel_errors")
	require.NoError(t, m.Steps(-1), "down 012 is a no-op")
	require.NoError(t, m.Steps(-1), "down 011 reverts the column default")
	require.Equal(t, "false", autoSummarizeDefault(t), "default is FALSE after the down migration")

	require.NoError(t, m.Steps(1), "up 011 re-applies the TRUE default")
	require.Equal(t, "true", autoSummarizeDefault(t))
	require.NoError(t, m.Steps(1), "up 012 runs clean (no FORCE RLS on fresh schema)")
	require.NoError(t, m.Steps(1), "up 013 creates channel_errors")
	require.NoError(t, m.Steps(1), "up 014 recreates channel_title")
	require.NoError(t, m.Steps(1), "up 015 reshapes transcripts to shared")
	require.NoError(t, m.Steps(1), "up 016 recreates channel_caption_state (HEAD)")
}

// channelTitleExists reports whether videos.channel_title is present.
func channelTitleExists(t *testing.T) bool {
	t.Helper()
	var exists bool
	require.NoError(t, rawPool(t).QueryRow(context.Background(),
		`SELECT EXISTS (SELECT 1 FROM information_schema.columns
		  WHERE table_name = 'videos' AND column_name = 'channel_title')`).Scan(&exists))
	return exists
}

// TestMigration014VideoChannelTitleUpDown proves 014 is reversible: down drops
// videos.channel_title, up recreates it.
func TestMigration014VideoChannelTitleUpDown(t *testing.T) {
	newStore(t) // latest (014 applied)
	require.True(t, channelTitleExists(t), "channel_title exists at latest migration")

	m := fileMigrator(t)
	require.NoError(t, m.Steps(-1), "down 016 drops channel_caption_state, channel_title intact")
	require.True(t, channelTitleExists(t), "016 down leaves channel_title intact")
	require.NoError(t, m.Steps(-1), "down 015 reshapes transcripts, channel_title intact")
	require.True(t, channelTitleExists(t), "015 down leaves channel_title intact")
	require.NoError(t, m.Steps(-1), "down 014 must drop channel_title")
	require.False(t, channelTitleExists(t), "channel_title must be gone after the down migration")

	require.NoError(t, m.Steps(1), "up 014 must recreate channel_title")
	require.True(t, channelTitleExists(t), "channel_title must be restored after the up migration")
	require.NoError(t, m.Steps(1), "up 015 restores the shared transcripts shape")
	require.NoError(t, m.Steps(1), "up 016 recreates channel_caption_state (HEAD)")
}

// TestMigration012FixAutoSummarizeRLS proves 012 runs cleanly and flips any
// remaining auto_summarize=FALSE rows to TRUE (the back-fill blocked by RLS in 011).
func TestMigration012FixAutoSummarizeRLS(t *testing.T) {
	newStore(t) // apply all migrations including 012
	require.Equal(t, "true", autoSummarizeDefault(t), "column default is TRUE after 012")

	// Round-trip: down 012, then up 012 — must be idempotent.
	m := fileMigrator(t)
	require.NoError(t, m.Steps(-1), "down 012 must not error")
	require.NoError(t, m.Steps(1), "up 012 must re-apply cleanly")
	require.Equal(t, "true", autoSummarizeDefault(t), "default still TRUE after 012 re-applied")
}
