const std = @import("std");
const util = @import("util");

const Uuid = util.Uuid;
const DateTime = util.DateTime;

pub const FileOwner = union(enum) {
    user_id: Uuid,
    community_id: Uuid,
};

pub const DriveFile = struct {
    id: Uuid,
    filename: []const u8,
    owner: FileOwner,
    size: usize,
    created_at: DateTime,
};

pub const files = struct {
    pub fn create(db: anytype, owner: FileOwner, filename: []const u8, data: []const u8, alloc: std.mem.Allocator) !void {
        const id = Uuid.randV4(util.getThreadPrng());
        const now = DateTime.now();

        // TODO: assert we're not in a transaction
        db.insert("drive_file", .{
            .id = id,
            .filename = filename,
            .account_owner_id = if (owner == .user_id) owner.user_id else null,
            .community_owner_id = if (owner == .community_id) owner.community_id else null,
            .created_at = now,
            .size = data.len,
        }, alloc) catch return error.DatabaseFailure;
        // Assume the previous statement succeeded and is not stuck in a transaction
        errdefer {
            db.exec("DELETE FROM drive_file WHERE ID = $1", .{id}, alloc) catch |err| {
                std.log.err("Unable to remove file record in DB: {}", .{err});
            };
        }

        try saveFile(id, data);
    }

    const data_root = "./files";
    fn saveFile(id: Uuid, data: []const u8) !void {
        var dir = try std.fs.cwd().openDir(data_root, .{});
        defer dir.close();

        var file = try dir.createFile(&id.toCharArray(), .{ .exclusive = true });
        defer file.close();

        try file.writer().writeAll(data);
        try file.sync();
    }

    pub fn deref(alloc: std.mem.Allocator, id: Uuid) ![]const u8 {
        var dir = try std.fs.cwd().openDir(data_root, .{});
        defer dir.close();

        return dir.readFileAlloc(alloc, &id.toCharArray(), 1 << 32);
    }

    pub fn delete(db: anytype, alloc: std.mem.Allocator, id: Uuid) !void {
        var dir = try std.fs.cwd().openDir(data_root, .{});
        defer dir.close();

        try dir.deleteFile(id.toCharArray());

        db.exec("DELETE FROM drive_file WHERE ID = $1", .{id}, alloc) catch return error.DatabaseFailure;
    }
};