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,

    path: []const u8,
    filename: []const u8,

    owner: FileOwner,

    size: usize,

    description: []const u8,
    content_type: []const u8,
    sensitive: bool,

    created_at: DateTime,
    updated_at: DateTime,
};

const EntryType = enum {
    dir,
    file,
};

pub const CreateFileArgs = struct {
    dir: []const u8,
    filename: []const u8,
    owner: FileOwner,
    created_by: Uuid,
    description: ?[]const u8,
    content_type: ?[]const u8,
    sensitive: bool,
};

fn lookupDirectory(db: anytype, owner: FileOwner, path: []const u8, alloc: std.mem.Allocator) !Uuid {
    return (try db.queryRow(
        std.meta.Tuple(
            &.{util.Uuid},
        ),
        \\SELECT id
        \\FROM drive_entry_path
        \\WHERE
        \\  path = (CASE WHEN LENGTH($1) = 0 THEN '/' ELSE '/' || $1 || '/' END)
        \\  AND account_owner_id IS NOT DISTINCT FROM $2
        \\  AND community_owner_id IS NOT DISTINCT FROM $3
        \\  AND kind = 'dir'
        \\LIMIT 1
    ,
        .{
            std.mem.trim(u8, path, "/"),
            if (owner == .user_id) owner.user_id else null,
            if (owner == .community_id) owner.community_id else null,
        },
        alloc,
    ))[0];
}

fn lookup(db: anytype, owner: FileOwner, path: []const u8, alloc: std.mem.Allocator) !Uuid {
    return (try db.queryRow(
        std.meta.Tuple(
            &.{util.Uuid},
        ),
        \\SELECT id
        \\FROM drive_entry_path
        \\WHERE
        \\  path = (CASE WHEN LENGTH($1) = 0 THEN '/' ELSE '/' || $1 || '/' END)
        \\  AND account_owner_id IS NOT DISTINCT FROM $2
        \\  AND community_owner_id IS NOT DISTINCT FROM $3
        \\LIMIT 1
    ,
        .{
            std.mem.trim(u8, path, "/"),
            if (owner == .user_id) owner.user_id else null,
            if (owner == .community_id) owner.community_id else null,
        },
        alloc,
    ))[0];
}

pub fn mkdir(db: anytype, owner: FileOwner, path: []const u8, alloc: std.mem.Allocator) !void {
    var split = std.mem.splitBackwards(u8, std.mem.trim(u8, path, "/"), "/");
    const name = split.first();
    const dir = split.rest();
    std.log.debug("'{s}' / '{s}'", .{ name, dir });

    if (name.len == 0) return error.EmptyName;

    const id = Uuid.randV4(util.getThreadPrng());

    const tx = try db.begin();
    errdefer tx.rollback();

    const parent = try lookupDirectory(tx, owner, dir, alloc);

    try tx.insert("drive_entry", .{
        .id = id,

        .account_owner_id = if (owner == .user_id) owner.user_id else null,
        .community_owner_id = if (owner == .community_id) owner.community_id else null,

        .name = name,
        .parent_directory_id = parent,
    }, alloc);
    try tx.commit();
}

pub fn rmdir(db: anytype, owner: FileOwner, path: []const u8, alloc: std.mem.Allocator) !void {
    const tx = try db.begin();
    errdefer tx.rollback();

    const id = try lookupDirectory(tx, owner, path, alloc);
    try tx.exec("DELETE FROM drive_directory WHERE id = $1", .{id}, alloc);
    try tx.commit();
}

fn insertFileRow(tx: anytype, id: Uuid, filename: []const u8, owner: FileOwner, dir: Uuid, alloc: std.mem.Allocator) !void {
    try tx.insert("drive_entry", .{
        .id = id,

        .account_owner_id = if (owner == .user_id) owner.user_id else null,
        .community_owner_id = if (owner == .community_id) owner.community_id else null,

        .parent_directory_id = dir,
        .name = filename,

        .file_id = id,
    }, alloc);
}

pub fn createFile(db: anytype, args: CreateFileArgs, data: []const u8, alloc: std.mem.Allocator) !void {
    const id = Uuid.randV4(util.getThreadPrng());
    const now = DateTime.now();

    {
        var tx = try db.begin();
        errdefer tx.rollback();

        const dir_id = try lookupDirectory(tx, args.owner, args.dir, alloc);

        try tx.insert("file_upload", .{
            .id = id,

            .filename = args.filename,

            .created_by = args.created_by,
            .size = data.len,

            .description = args.description,
            .content_type = args.content_type,
            .sensitive = args.sensitive,

            .is_deleted = false,

            .created_at = now,
            .updated_at = now,
        }, alloc);

        var sub_tx = try tx.savepoint();
        if (insertFileRow(sub_tx, id, args.filename, args.owner, dir_id, alloc)) |_| {
            try sub_tx.release();
        } else |err| {
            std.log.debug("{}", .{err});
            switch (err) {
                error.UniqueViolation => {
                    try sub_tx.rollbackSavepoint();
                    // Rename the file before trying again
                    var split = std.mem.split(u8, args.filename, ".");
                    const name = split.first();
                    const ext = split.rest();
                    var buf: [256]u8 = undefined;
                    const drive_filename = try std.fmt.bufPrint(&buf, "{s}.{}.{s}", .{ name, id, ext });
                    try insertFileRow(tx, id, drive_filename, args.owner, dir_id, alloc);
                },
                else => return error.DatabaseFailure,
            }
        }

        try tx.commit();
    }

    errdefer {
        db.exec("DELETE FROM file_upload WHERE ID = $1", .{id}, alloc) catch |err| {
            std.log.err("Unable to remove file record in DB: {}", .{err});
        };
        db.exec("DELETE FROM drive_entry 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 deleteFile(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());

    const tx = try db.beginOrSavepoint();
    errdefer tx.rollback();

    tx.exec("DELETE FROM drive_entry WHERE ID = $1", .{id}, alloc) catch return error.DatabaseFailure;
    tx.exec("DELETE FROM file_upload WHERE ID = $1", .{id}, alloc) catch return error.DatabaseFailure;
    try tx.commitOrRelease();
}