package store

import (
	"crypto/sha256"
	"database/sql"
	"encoding/hex"
	"fmt"
	"strings"
	"time"
)

// Operator access tokens (hub v0.152.0, `05` §17). A token is a scoped, expiring stand-in for the operator password,
// for scripts (Claude Code's floor step first). The plain token is shown ONCE at creation and never stored: the row
// keeps only its unkeyed SHA-256. A slow hash is not needed — the token is 32 random bytes, so there is nothing to
// guess and nothing a dictionary can find; the hash only stops a leaked database copy from being replayed as a token.
// Pinned by TestAPIToken_StoredRowHasNoPlainToken.

// APITokenPrefix starts every operator access token. The web surface accepts it; the box API refuses it.
const APITokenPrefix = "fhp_"

// APIToken is one access-token row. The plain token is never a field here.
type APIToken struct {
	ID           int64
	Name         string
	Scopes       []string // "<group>:read" / "<group>:write" — validated by the web package's scope list
	CreatedAt    time.Time
	CreatedBy    string
	ExpiresAt    time.Time
	LastUsedAt   *time.Time
	LastUsedFrom string
	RevokedAt    *time.Time
}

// Expired reports whether the token's expiry has passed at now.
func (t *APIToken) Expired(now time.Time) bool { return !now.Before(t.ExpiresAt) }

// HashAPIToken is the stored lookup form of a plain token.
func HashAPIToken(plain string) string {
	sum := sha256.Sum256([]byte(plain))
	return hex.EncodeToString(sum[:])
}

func (s *Store) migrateAPITokens() error {
	_, err := s.db.Exec(`
		CREATE TABLE IF NOT EXISTS api_tokens (
			id             INTEGER PRIMARY KEY AUTOINCREMENT,
			name           TEXT NOT NULL,
			token_hash     TEXT NOT NULL UNIQUE,
			scopes         TEXT NOT NULL,
			created_at     DATETIME NOT NULL,
			created_by     TEXT NOT NULL DEFAULT '',
			expires_at     DATETIME NOT NULL,
			last_used_at   DATETIME,
			last_used_from TEXT NOT NULL DEFAULT '',
			revoked_at     DATETIME
		);`)
	return err
}

// CreateAPIToken stores a new token by its hash. The caller generated plain and shows it once.
func (s *Store) CreateAPIToken(name, plain string, scopes []string, createdBy string, expiresAt time.Time) (int64, error) {
	name = strings.TrimSpace(name)
	if name == "" {
		return 0, fmt.Errorf("token name is empty")
	}
	if len(scopes) == 0 {
		return 0, fmt.Errorf("token has no scope")
	}
	res, err := s.db.Exec(`INSERT INTO api_tokens (name, token_hash, scopes, created_at, created_by, expires_at)
		VALUES (?, ?, ?, ?, ?, ?)`,
		name, HashAPIToken(plain), strings.Join(scopes, ","), time.Now().UTC().Format(time.RFC3339),
		createdBy, expiresAt.UTC().Format(time.RFC3339))
	if err != nil {
		return 0, err
	}
	return res.LastInsertId()
}

const apiTokenCols = `id, name, scopes, created_at, created_by, expires_at, last_used_at, last_used_from, revoked_at`

func scanAPIToken(sc interface{ Scan(...any) error }) (*APIToken, error) {
	var t APIToken
	var scopes, created, expires string
	var lastUsed, revoked sql.NullString
	if err := sc.Scan(&t.ID, &t.Name, &scopes, &created, &t.CreatedBy, &expires, &lastUsed, &t.LastUsedFrom, &revoked); err != nil {
		return nil, err
	}
	if scopes != "" {
		t.Scopes = strings.Split(scopes, ",")
	}
	t.CreatedAt = parseSQLiteTime(created)
	t.ExpiresAt = parseSQLiteTime(expires)
	if lastUsed.Valid && lastUsed.String != "" {
		v := parseSQLiteTime(lastUsed.String)
		t.LastUsedAt = &v
	}
	if revoked.Valid && revoked.String != "" {
		v := parseSQLiteTime(revoked.String)
		t.RevokedAt = &v
	}
	return &t, nil
}

// GetAPITokenByPlain finds a token by its plain value (hashed here). nil, nil = no such token.
func (s *Store) GetAPITokenByPlain(plain string) (*APIToken, error) {
	t, err := scanAPIToken(s.db.QueryRow(`SELECT `+apiTokenCols+` FROM api_tokens WHERE token_hash = ?`, HashAPIToken(plain)))
	if err == sql.ErrNoRows {
		return nil, nil
	}
	return t, err
}

// ListAPITokens returns every token, newest first (revoked ones included — the list is the audit trail).
func (s *Store) ListAPITokens() ([]*APIToken, error) {
	rows, err := s.db.Query(`SELECT ` + apiTokenCols + ` FROM api_tokens ORDER BY id DESC`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []*APIToken
	for rows.Next() {
		t, err := scanAPIToken(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, t)
	}
	return out, rows.Err()
}

// RevokeAPIToken marks a token revoked. Revoking twice is a no-op; an unknown id is an error.
func (s *Store) RevokeAPIToken(id int64) error {
	res, err := s.db.Exec(`UPDATE api_tokens SET revoked_at = COALESCE(revoked_at, ?) WHERE id = ?`,
		time.Now().UTC().Format(time.RFC3339), id)
	if err != nil {
		return err
	}
	if n, _ := res.RowsAffected(); n == 0 {
		return fmt.Errorf("no token with id %d", id)
	}
	return nil
}

// TouchAPIToken records a use. Best effort: a failure here never refuses the request.
func (s *Store) TouchAPIToken(id int64, from string) error {
	_, err := s.db.Exec(`UPDATE api_tokens SET last_used_at = ?, last_used_from = ? WHERE id = ?`,
		time.Now().UTC().Format(time.RFC3339), from, id)
	return err
}