// Package accounts implements the MailProvider abstraction: one interface,
// multiple backends (local GoMail account, generic IMAP/SMTP, and — Phase 10 —
// Gmail/M365 native APIs). The webmail client (later phase) talks to every
// linked account through this same interface regardless of where the mail
// actually lives.
package accounts

import "context"

type Folder struct {
	ID          string `json:"id"` // provider-native folder identifier (IMAP mailbox name, etc.)
	DisplayName string `json:"display_name"`
	Type        string `json:"type"` // inbox|sent|drafts|trash|junk|custom
	UnreadCount int    `json:"unread_count"`
	TotalCount  int    `json:"total_count"`
}

type MessageHeader struct {
	ID        string   `json:"id"` // provider-native message identifier (IMAP UID, etc.)
	FolderID  string   `json:"folder_id"`
	From      string   `json:"from"`
	To        string   `json:"to"`
	Subject   string   `json:"subject"`
	Date      string   `json:"date"`
	Flags     []string `json:"flags"`
	SizeBytes int64    `json:"size_bytes"`
}

type FullMessage struct {
	MessageHeader
	Raw []byte `json:"raw"` // full RFC 5322 message; json.Marshal base64-encodes []byte automatically
}

type OutgoingMessage struct {
	From    string   `json:"from"`
	To      []string `json:"to"`
	CC      []string `json:"cc"`
	BCC     []string `json:"bcc"`
	Subject string   `json:"subject"`
	Body    string   `json:"body"` // plain text; HTML composer is a webmail-phase concern
}

type ListOpts struct {
	Limit  int
	Offset int
}

type SyncResult struct {
	NewCursor    string
	NewMessages  []MessageHeader
	DeletedIDs   []string
	FlagsChanged map[string][]string // messageID -> new flags
}

// MailProvider is implemented once per account type. Every method takes a
// context so network-backed implementations (IMAP, and later Gmail/Graph
// API) can be cancelled/timed-out uniformly with the local implementation.
type MailProvider interface {
	ListFolders(ctx context.Context) ([]Folder, error)
	ListMessages(ctx context.Context, folderID string, opts ListOpts) ([]MessageHeader, error)
	GetMessage(ctx context.Context, folderID, messageID string) (*FullMessage, error)
	SendMessage(ctx context.Context, msg *OutgoingMessage) error
	SetFlags(ctx context.Context, folderID, messageID string, flags []string) error
	Move(ctx context.Context, folderID, messageID, destFolderID string) error
	Delete(ctx context.Context, folderID, messageID string) error
	Sync(ctx context.Context, since string) (*SyncResult, error)
}