// Package storage provides session storage operations for the OIDC middleware
package storage

import (
	"fmt"
	"net/http"
	"sync"

	"github.com/gorilla/sessions"
)

// SessionData represents a user's authentication session with comprehensive token management.
// It handles main session data and supports large tokens that need to be
// split across multiple cookies due to browser size limitations.
type SessionData struct {
	manager            SessionManager
	request            *http.Request
	mainSession        *sessions.Session
	accessSession      *sessions.Session
	refreshSession     *sessions.Session
	idTokenSession     *sessions.Session
	accessTokenChunks  map[int]*sessions.Session
	refreshTokenChunks map[int]*sessions.Session
	idTokenChunks      map[int]*sessions.Session
	refreshMutex       sync.Mutex
	sessionMutex       sync.RWMutex
	dirty              bool
	inUse              bool
}

// SessionManager interface for session management operations
type SessionManager interface {
	GetSessionOptions(isSecure bool) *sessions.Options
	EnhanceSessionSecurity(options *sessions.Options, r *http.Request) *sessions.Options
	GetLogger() Logger
}

// Logger interface for dependency injection
type Logger interface {
	Error(msg string)
	Errorf(format string, args ...interface{})
}

// NewSessionData creates a new session data instance
func NewSessionData(manager SessionManager) *SessionData {
	return &SessionData{
		manager:            manager,
		accessTokenChunks:  make(map[int]*sessions.Session),
		refreshTokenChunks: make(map[int]*sessions.Session),
		idTokenChunks:      make(map[int]*sessions.Session),
		refreshMutex:       sync.Mutex{},
		sessionMutex:       sync.RWMutex{},
		dirty:              false,
		inUse:              false,
	}
}

// IsDirty returns true if the session data has been modified since it was last loaded or saved.
// This is used to optimize session saves by only writing when necessary.
func (sd *SessionData) IsDirty() bool {
	return sd.dirty
}

// MarkDirty marks the session as having pending changes that need to be saved.
// This is used when session data hasn't changed in content but should still
// trigger a session save (e.g., to ensure the cookie is re-issued).
func (sd *SessionData) MarkDirty() {
	sd.dirty = true
}

// Save persists all session data including main session and token chunks.
// It applies security options, saves all session components, and handles
// errors gracefully by continuing to save other components even if one fails.
func (sd *SessionData) Save(r *http.Request, w http.ResponseWriter) error {
	isSecure := r.Header.Get("X-Forwarded-Proto") == "https" || r.TLS != nil
	if forceHTTPS := sd.manager.GetLogger(); forceHTTPS != nil {
		// Add force HTTPS check if needed
	}

	options := sd.manager.GetSessionOptions(isSecure)
	options = sd.manager.EnhanceSessionSecurity(options, r)

	if sd.mainSession != nil {
		sd.mainSession.Options = options
	}
	if sd.accessSession != nil {
		sd.accessSession.Options = options
	}
	if sd.refreshSession != nil {
		sd.refreshSession.Options = options
	}
	if sd.idTokenSession != nil {
		sd.idTokenSession.Options = options
	}

	var firstErr error
	saveOrLogError := func(s *sessions.Session, name string) {
		if s == nil {
			logger := sd.manager.GetLogger()
			if logger != nil {
				logger.Errorf("Attempted to save nil session: %s", name)
			}
			if firstErr == nil {
				firstErr = fmt.Errorf("attempted to save nil session: %s", name)
			}
			return
		}
		if err := s.Save(r, w); err != nil {
			errMsg := fmt.Errorf("failed to save %s session: %w", name, err)
			logger := sd.manager.GetLogger()
			if logger != nil {
				logger.Error(errMsg.Error())
			}
			if firstErr == nil {
				firstErr = errMsg
			}
		}
	}

	saveOrLogError(sd.mainSession, "main")
	saveOrLogError(sd.accessSession, "access token")
	saveOrLogError(sd.refreshSession, "refresh token")
	saveOrLogError(sd.idTokenSession, "ID token")

	for i, sessionChunk := range sd.accessTokenChunks {
		if sessionChunk != nil {
			sessionChunk.Options = options
			saveOrLogError(sessionChunk, fmt.Sprintf("access token chunk %d", i))
		}
	}

	for i, sessionChunk := range sd.refreshTokenChunks {
		if sessionChunk != nil {
			sessionChunk.Options = options
			saveOrLogError(sessionChunk, fmt.Sprintf("refresh token chunk %d", i))
		}
	}

	for i, sessionChunk := range sd.idTokenChunks {
		if sessionChunk != nil {
			sessionChunk.Options = options
			saveOrLogError(sessionChunk, fmt.Sprintf("ID token chunk %d", i))
		}
	}

	if firstErr == nil {
		sd.dirty = false
	}
	return firstErr
}

// Clear completely clears all session data and safely returns the session to the pool.
// It removes all authentication data, expires cookies, and handles panic recovery.
func (sd *SessionData) Clear(r *http.Request, w http.ResponseWriter) error {
	defer func() {
		sd.returnToPoolSafely()
	}()

	sd.sessionMutex.Lock()
	defer sd.sessionMutex.Unlock()

	sd.clearAllSessionData(r, true)

	// This is primarily for testing - in production w will often be nil
	var err error
	if w != nil {
		if r != nil && r.Header.Get("X-Test-Error") == "true" {
			if sd.mainSession != nil {
				sd.mainSession.Values["error_trigger"] = func() {}
			}
		}

		err = sd.Save(r, w)
	}

	sd.request = nil
	return err
}

// clearAllSessionData clears all session data including main session and token chunks.
// It removes all session values and optionally expires all associated cookies.
func (sd *SessionData) clearAllSessionData(r *http.Request, expire bool) {
	clearSessionValues(sd.mainSession, expire)
	clearSessionValues(sd.accessSession, expire)
	clearSessionValues(sd.refreshSession, expire)
	clearSessionValues(sd.idTokenSession, expire)

	if expire && r != nil {
		sd.clearTokenChunks(r, sd.accessTokenChunks)
		sd.clearTokenChunks(r, sd.refreshTokenChunks)
		sd.clearTokenChunks(r, sd.idTokenChunks)
	} else {
		for k := range sd.accessTokenChunks {
			delete(sd.accessTokenChunks, k)
		}
		for k := range sd.refreshTokenChunks {
			delete(sd.refreshTokenChunks, k)
		}
		for k := range sd.idTokenChunks {
			delete(sd.idTokenChunks, k)
		}
	}

	if expire {
		sd.dirty = true
	}
}

// clearSessionValues removes all values from a session and optionally expires it.
// This is used during session cleanup and logout operations.
func clearSessionValues(session *sessions.Session, expire bool) {
	if session == nil {
		return
	}

	for k := range session.Values {
		delete(session.Values, k)
	}

	if expire {
		session.Options.MaxAge = -1
	}
}

// clearTokenChunks clears token chunks from the session
func (sd *SessionData) clearTokenChunks(r *http.Request, chunks map[int]*sessions.Session) {
	for i, chunk := range chunks {
		if chunk != nil {
			clearSessionValues(chunk, true)
		}
		delete(chunks, i)
	}
}

// returnToPoolSafely safely returns the session to the object pool
func (sd *SessionData) returnToPoolSafely() {
	defer func() {
		if r := recover(); r != nil {
			logger := sd.manager.GetLogger()
			if logger != nil {
				logger.Errorf("Panic during session pool return: %v", r)
			}
		}
	}()

	sd.sessionMutex.Lock()
	defer sd.sessionMutex.Unlock()

	if sd.inUse {
		sd.inUse = false
		sd.Reset()
		// Pool return should be handled by calling code
	}
}

// Reset resets the session data to a clean state
func (sd *SessionData) Reset() {
	sd.mainSession = nil
	sd.accessSession = nil
	sd.refreshSession = nil
	sd.idTokenSession = nil

	// Clear maps without recreating them
	for k := range sd.accessTokenChunks {
		delete(sd.accessTokenChunks, k)
	}
	for k := range sd.refreshTokenChunks {
		delete(sd.refreshTokenChunks, k)
	}
	for k := range sd.idTokenChunks {
		delete(sd.idTokenChunks, k)
	}

	sd.dirty = false
	sd.inUse = false
	sd.request = nil
}

// SetSessions sets the session objects
func (sd *SessionData) SetSessions(main, access, refresh, idToken *sessions.Session) {
	sd.mainSession = main
	sd.accessSession = access
	sd.refreshSession = refresh
	sd.idTokenSession = idToken
}

// GetMainSession returns the main session
func (sd *SessionData) GetMainSession() *sessions.Session {
	return sd.mainSession
}

// GetAccessSession returns the access token session
func (sd *SessionData) GetAccessSession() *sessions.Session {
	return sd.accessSession
}

// GetRefreshSession returns the refresh token session
func (sd *SessionData) GetRefreshSession() *sessions.Session {
	return sd.refreshSession
}

// GetIDTokenSession returns the ID token session
func (sd *SessionData) GetIDTokenSession() *sessions.Session {
	return sd.idTokenSession
}

// GetTokenChunks returns the token chunk maps
func (sd *SessionData) GetTokenChunks() (map[int]*sessions.Session, map[int]*sessions.Session, map[int]*sessions.Session) {
	return sd.accessTokenChunks, sd.refreshTokenChunks, sd.idTokenChunks
}

// SetInUse marks the session as in use
func (sd *SessionData) SetInUse(inUse bool) {
	sd.inUse = inUse
}

// IsInUse returns whether the session is in use
func (sd *SessionData) IsInUse() bool {
	return sd.inUse
}