derploader/src/main.zig

const std = @import("std");
const sqlite = @import("sqlite");
const clap = @import("clap");
const curl = @cImport({
    @cInclude("curl/curl.h");
});

const uri = @import("uri");
const json = @import("json");

const log = std.log.scoped(.derploader);

const params = [_]clap.Param(clap.Help){
    clap.parseParam("-h, --help          Display this help and exit.") catch unreachable,
    clap.parseParam("-c, --create=<PATH> Create new database at PATH.") catch unreachable,
    clap.parseParam("-i <ID>...          Operate on ID.") catch unreachable,
    clap.parseParam("-a                  Operate on all IDs in the database.") catch unreachable,
    clap.parseParam("-l <FILE>...        Operate on IDs from a file.") catch unreachable,
    clap.parseParam("-m                  Download metadata for ID image.") catch unreachable,
    clap.parseParam("-d                  Download image data of ID.") catch unreachable,
    clap.parseParam("-e                  Extract image to local subfolder.") catch unreachable,
    clap.parseParam("-t <MILLIS>         Time between requests.") catch unreachable,
    clap.parseParam("-r                  Register ID.") catch unreachable,
    clap.parseParam("-k                  Include key in searches from environment variable DERPI_KEY.") catch unreachable,
    clap.parseParam("-s <SEARCH>...      Iterate over the results of searches.") catch unreachable,
    clap.parseParam("-o <ORDER>          Order searches by ORDER, descending.") catch unreachable,
    clap.parseParam("-O <ORDER>          Order searches by ORDER, ascending.") catch unreachable,
    clap.parseParam("-p <PAGE>           Start from page PAGE.") catch unreachable,
    clap.parseParam("-P <PAGES>          Stop after PAGES pages.") catch unreachable,
    clap.parseParam("--migrate           Update an old database.") catch unreachable,
    clap.parseParam("--yolo              PRAGMA synchronous = OFF") catch unreachable,
};

fn printFullUsage(w: anytype) !void {
    _ = try w.print("{s} ", .{std.os.argv[0]});
    try clap.usage(w, &params);
    _ = try w.writeByte('\n');
    try clap.help(w, &params);
    return;
}

fn sqliteErrorReport(str: []const u8, db: *sqlite.Db) void {
    log.err("{s}: {}", .{ str, db.getDetailedError() });
}

fn curlErrorReport(str: []const u8, code: curl.CURLcode) void {
    log.err("{s}: {s} {s}", .{ str, curl.curl_easy_strerror(code), curlerr[0.. :0] });
}

const create =
    \\CREATE TABLE IF NOT EXISTS image(
    \\  iid INTEGER PRIMARY KEY,
    \\  eid INTEGER UNIQUE,
    \\  metadata TEXT,
    \\  full_url TEXT GENERATED ALWAYS AS
    \\    (json_extract(metadata, '$.image.representations.full')) VIRTUAL,
    \\  thumb_url TEXT GENERATED ALWAYS AS
    \\    (json_extract(metadata, '$.image.representations.thumb')) VIRTUAL,
    \\  extension TEXT GENERATED ALWAYS AS
    \\    (json_extract(metadata, '$.image.format')) VIRTUAL,
    \\  hash_meta TEXT,
    \\  image_id INTEGER,
    \\  thumb_id INTEGER
    \\);
;

const metatable =
    \\CREATE TABLE IF NOT EXISTS derpiloader(
    \\  name TEXT,
    \\  value
    \\);
;

pub fn insertMeta(db: *sqlite.Db, id: u64, meta: []const u8) !void {
    const q =
        \\INSERT OR ROLLBACK INTO image (id, metadata) VALUES (?, ?);
    ;
    try db.exec(q, .{}, .{ .id = id, .metadata = meta });
}

const api_base = "https://derpibooru.org/api/v1/json";

var urlbuf = [_:0]u8{0} ** 512;
var curlerr = [_:0]u8{0} ** (curl.CURL_ERROR_SIZE);

const hash_prefix = "blake3-";
var hash_buf = [_]u8{0} ** (std.crypto.hash.Blake3.digest_length);
var hash_buf2 = [_]u8{0} ** (std.crypto.hash.Blake3.digest_length * 2 + hash_prefix[0..].len);

fn hashit(input: []const u8) !void {
    std.crypto.hash.Blake3.hash(input, hash_buf[0..], .{});
    _ = try std.fmt.bufPrint(
        hash_buf2[0..],
        hash_prefix ++ "{s}",
        .{std.fmt.fmtSliceHexLower(hash_buf[0..])},
    );
}

var fetch_timer: ?std.time.Timer = null;
var fetch_wait: u64 = 0;
var first_fetch = true;

pub fn main() anyerror!void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    const alloc = &gpa.allocator;

    var diag = clap.Diagnostic{};
    var args = clap.parse(
        clap.Help,
        &params,
        .{ .diagnostic = &diag, .allocator = alloc },
    ) catch |err| {
        // Report useful error and exit
        diag.report(std.io.getStdErr().writer(), err) catch {};
        return;
    };
    defer args.deinit();

    if (args.flag("-h")) {
        var w = std.io.getStdOut().writer();
        try printFullUsage(w);
        return;
    }

    const filename = "test.db3";
    var db = try sqlite.Db.init(.{
        .mode = sqlite.Db.Mode{ .File = filename },
        .open_flags = .{
            .write = true,
            .create = true,
        },
        .threading_mode = .SingleThread,
    });
    db.exec(create, .{}, .{ 0, 0, 0 }) catch sqliteErrorReport("Couldn't create table", &db);

    if (args.flag("--migrate")) {
        if (args.flag("--yolo")) try db.exec("PRAGMA synchronous=0;", .{}, .{});
        try db.exec("BEGIN IMMEDIATE;", .{}, .{});
        errdefer db.exec("ROLLBACK;", .{}, .{}) catch std.debug.panic("SQLite database errored trying to roll back. Have fun!", .{});
        var stmt = try db.prepare("SELECT ROWID FROM image;");
        defer stmt.deinit();
        var iter = try stmt.iterator(u64, .{});
        while (try iter.next(.{})) |id| {
            try db.exec(
                \\INSERT INTO blob (data, hash)
                \\  SELECT image, hash_full
                \\  FROM image WHERE ROWID = ?;
            , .{}, .{id});
            try db.exec(
                \\UPDATE image
                \\  SET image_id = last_insert_rowid()
                \\  WHERE ROWID = ?
            , .{}, .{id});
            try db.exec(
                \\INSERT INTO blob (data, hash)
                \\  SELECT thumb, hash_thumb
                \\  FROM image WHERE ROWID = ?;
            , .{}, .{id});
            try db.exec(
                \\UPDATE image
                \\  SET thumb_id = last_insert_rowid()
                \\  WHERE ROWID = ?
            , .{}, .{id});
        }
        db.exec("COMMIT;", .{}, .{}) catch std.debug.panic("SQLite database errored trying to commit. Not *terrible*, I guess.", .{});
        return;
    }

    var ret = curl.curl_global_init(curl.CURL_GLOBAL_ALL);
    if (ret != curl.CURLE_OK) {
        log.err("cURL global init failure: {s}", .{curl.curl_easy_strerror(ret)});
        return;
    }
    defer curl.curl_global_cleanup();
    const handle = curl.curl_easy_init() orelse return error.CURLHandleInitFailed;
    defer curl.curl_easy_cleanup(handle);
    var response_buffer = std.ArrayList(u8).init(alloc);
    defer response_buffer.deinit();

    _ = curl.curl_easy_setopt(handle, curl.CURLOPT_ERRORBUFFER, &curlerr);

    const key = std.os.getenv("DERPI_KEY") orelse null;

    if (args.option("-t")) |millis_str| {
        const millis = std.fmt.parseInt(u64, millis_str, 10) catch {
            log.err("Fetch wait time must be a positive integer denoting some number of milliseconds.", .{});
            return;
        };
        fetch_wait = millis;
    }

    for (args.options("-i")) |id_str| {
        log.info("Iterating over all specified command line IDs.", .{});
        const id = std.fmt.parseInt(u64, id_str, 10) catch {
            log.err("Image ID must be a positive integer.", .{});
            continue;
        };
        log.info("Operating on ID {d}, per -i.", .{id});
        runActions(&db, id, &response_buffer, alloc, handle, &args, null);
    }

    if (args.flag("-a")) {
        log.info("Iterating over all registered IDs.", .{});
        var stmt = try db.prepare("SELECT id FROM image WHERE id IS NOT NULL");
        defer stmt.deinit();
        var iter = try stmt.iterator(u64, .{});
        while (try iter.next(.{})) |id| {
            log.info("Operating on ID {d}, per -a.", .{id});
            runActions(&db, id, &response_buffer, alloc, handle, &args, null);
        }
    }

    for (args.options("-l")) |path| {
        log.info("Iterating over IDs listed in {s}.", .{path});
        var file = std.fs.cwd().openFile(path, .{ .read = true }) catch |err| {
            log.err("Couldn't open file {s}: {}", .{ path, err });
            continue;
        };
        defer file.close();
        var reader = file.reader();
        var buffer: [128]u8 = undefined;
        while (try reader.readUntilDelimiterOrEof(&buffer, '\n')) |id_str| {
            const id = std.fmt.parseInt(u64, id_str, 10) catch {
                log.err("Image ID must be a positive integer.", .{});
                continue;
            };
            log.info("Operating on ID {d}, per -l.", .{id});
            runActions(&db, id, &response_buffer, alloc, handle, &args, null);
        }
    }

    const searches = args.options("-s");
    if (searches.len > 0) {
        //var reader = std.io.fixedBufferStream(
        //    @embedFile("/etc/ssl/certs/ca-certificates.crt"),
        //).reader();
        //const trust = try tls.x509.CertificateChain.from_pem(alloc, reader);
        // catch |a| {
        //     log.err("Something dun fucked with the certs: {}", .{a});
        //     return;
        // };
        const sort_ascending = args.option("-O");
        const sort_descending = args.option("-o");
        const sort_order = if (sort_ascending) |_| blk: {
            if (sort_descending) |_| {
                log.err("Can't sort up *and* down, dummy.", .{});
                return;
            } else {
                break :blk "asc";
            }
        } else blk: {
            if (sort_descending) |_| {
                break :blk "desc";
            } else {
                break :blk "desc";
            }
        };
        const sort_by = sort_descending orelse sort_ascending orelse "id";
        var page = if (args.option("-p")) |page| blk: {
            break :blk std.fmt.parseInt(u64, page, 10) catch {
                log.err("Page must be a positive integer.", .{});
                return;
            };
        } else 1;

        var maxPages = if (args.option("-P")) |nr| blk: {
            break :blk std.fmt.parseInt(u64, nr, 10) catch {
                log.err("Pages maximum must be a positive integer.", .{});
                return;
            };
        } else 0;

        const kkey: []const u8 = key orelse "";
        const aaaa: []const u8 = if (key) |_| "&key=" else "";
        var fuckme = std.ArrayList(u8).init(alloc);
        defer fuckme.deinit();
        for (searches) |search| {
            const esearch = try uri.escapeString(alloc, search);
            var pages: u64 = 0;
            log.info("Iterating over search \"{s}\", starting on page {d}.", .{ search, page });
            fuck: while (true) {
                pages += 1;
                if (maxPages > 0 and pages == maxPages) {
                    return;
                }
                log.info("Doing page {d}, {d}/{d}.", .{ page, pages, maxPages });
                _ = try std.fmt.bufPrintZ(
                    urlbuf[0..],
                    api_base ++ "/search/images?q={s}&page={d}&sd={s}&sf={s}&per_page=50{s}{s}",
                    .{
                        esearch, page, sort_order, sort_by, aaaa, kkey,
                    },
                );
                fuckme.clearRetainingCapacity();
                try easyFetch(handle, &urlbuf, &fuckme);
                const val = try json.parse(alloc, fuckme.items);
                if (val.get(.{"images"})) |aa| {
                    if (unwrap(aa, .Array)) |images| {
                        for (images) |i| {
                            var buffer: [1024 * 20]u8 = undefined;
                            const pid = unwrap(i.get("id") orelse {
                                log.err("Malformed reply from Derpi.", .{});
                                return;
                            }, .Int) orelse {
                                log.err("Malformed reply from Derpi, but in a different way.", .{});
                                return;
                            };
                            const id = if (pid >= 0) @intCast(u64, pid) else {
                                log.err("Malformed reply from Derpi, but in a third way.", .{});
                                return;
                            };
                            var aaa = std.io.fixedBufferStream(buffer[0..]).writer();
                            const data = json.Value{ .Object = &[_]json.Member{
                                json.Member{
                                    .key = "image",
                                    .value = i,
                                },
                            } };
                            try data.format("", .{}, aaa);
                            const jason = buffer[0..aaa.context.pos];
                            runActions(
                                &db,
                                id,
                                &response_buffer,
                                alloc,
                                handle,
                                &args,
                                jason,
                            );
                        }
                        if (images.len == 50) {
                            page += 1;
                        } else {
                            break :fuck;
                        }
                    }
                }
            }
            page = 1;
        }
    }
}

pub fn unwrap(
    un: anytype,
    comptime tag: std.meta.Tag(@TypeOf(un)),
) ?std.meta.TagPayload(@TypeOf(un), tag) {
    if (un != tag) return null;
    return @field(un, @tagName(tag));
}

fn runActions(
    db: *sqlite.Db,
    id: u64,
    resp: *std.ArrayList(u8),
    alloc: *std.mem.Allocator,
    handle: *curl.CURL,
    args: anytype,
    meta: ?[]const u8,
) void {
    if (args.flag("-r")) {
        registerID(db, id) catch |e| switch (e) {
            error.GO_ON => {},
            error.FATAL => {
                db.deinit();
                std.os.exit(1);
            },
            else => {
                db.deinit();
                std.os.exit(2);
            },
        };
    }
    if (args.flag("-m")) {
        if (meta) |m| {
            storeMetadata(db, id, m) catch |e| switch (e) {
                error.GO_ON => {},
                error.FATAL => {
                    db.deinit();
                    std.os.exit(1);
                },
                else => {
                    db.deinit();
                    std.os.exit(2);
                },
            };
        } else {
            getMetadata(db, id, resp, handle) catch |e| switch (e) {
                error.GO_ON => {},
                error.FATAL => {
                    db.deinit();
                    std.os.exit(1);
                },
                else => {
                    db.deinit();
                    std.os.exit(2);
                },
            };
        }
    }
    resp.clearRetainingCapacity();
    std.mem.set(u8, hash_buf[0..], 0);
    std.mem.set(u8, hash_buf2[0..], 0);
    if (args.flag("-d")) {
        getImage(db, id, resp, alloc, handle) catch |e| switch (e) {
            error.GO_ON => {},
            error.FATAL => {
                db.deinit();
                std.os.exit(1);
            },
            else => {
                db.deinit();
                std.os.exit(2);
            },
        };
    }
    resp.clearRetainingCapacity();
    std.mem.set(u8, hash_buf[0..], 0);
    std.mem.set(u8, hash_buf2[0..], 0);
    if (args.flag("-e")) {
        extractImage(db, id, alloc) catch |e| switch (e) {
            error.GO_ON => {},
            else => {
                db.deinit();
                std.os.exit(2);
            },
        };
    }
}

fn registerID(db: *sqlite.Db, id: u64) !void {
    log.info("Registering ID {d}.", .{id});
    const foo = db.one(
        bool,
        "SELECT true FROM image WHERE id = ?;",
        .{},
        .{ .id = id },
    ) catch {
        sqliteErrorReport("SQLite error while checking if ID already present", db);
        return error.GO_ON;
    };
    if (foo) |_| {
        log.info("ID {d} already registered.", .{id});
        return;
    }
    try db.exec("BEGIN IMMEDIATE", .{}, .{});
    errdefer db.exec("ROLLBACK;", .{}, .{}) catch {};
    db.exec(
        \\INSERT OR ROLLBACK
        \\  INTO image (id)
        \\  VALUES (?);
    , .{}, .{ .id = id }) catch {
        sqliteErrorReport("Couldn't insert ID into database.", db);
        return error.GO_ON;
    };

    db.exec("COMMIT", .{}, .{}) catch {
        sqliteErrorReport("FATAL: couldn't commit database", db);
        return error.FATAL;
    };
}

fn storeMetadata(
    db: *sqlite.Db,
    id: u64,
    metadata: []const u8,
) !void {
    log.info("Storing metadata for ID {d}.", .{id});
    const foobar = db.one(
        bool,
        "SELECT true FROM image WHERE id = ? AND metadata IS NOT NULL;",
        .{},
        .{ .id = id },
    ) catch {
        sqliteErrorReport("SQLite error while checking for metadata precence.", db);
        return error.GO_ON;
    };
    if (foobar) |_| {
        log.info("Metadata for ID {d} already acquired. Use -u to replace.", .{id});
        return;
    }
    const valid = std.json.validate(metadata);

    if (valid) {
        try db.exec("BEGIN IMMEDIATE;", .{}, .{});
        errdefer db.exec("ROLLBACK;", .{}, .{}) catch {};
        db.exec(
            \\INSERT OR ROLLBACK
            \\  INTO
            \\    image (id, metadata)
            \\    VALUES (?, ?)
            \\  ON CONFLICT (id)
            \\    DO UPDATE
            \\    SET metadata=excluded.metadata;
        , .{}, .{ .id = id, .metadata = metadata }) catch {
            sqliteErrorReport("Couldn't add metadata for ID {d} to database.", db);
            return error.GO_ON;
        };
        hashit(metadata) catch |err| {
            log.err("Couldn't hash metadata for ID {d}: {s}", .{ id, err });
            return error.GO_ON;
        };
        db.exec(
            "UPDATE OR ROLLBACK image SET hash_meta = ? WHERE id = ?",
            .{},
            .{ hash_buf2[0..], id },
        ) catch {
            sqliteErrorReport("Couldn't set metadata hash", db);
            return error.GO_ON;
        };
        db.exec("COMMIT", .{}, .{}) catch {
            sqliteErrorReport("FATAL: couldn't commit database", db);
            return error.FATAL;
        };
    }
}

fn getMetadata(
    db: *sqlite.Db,
    id: u64,
    resp: *std.ArrayList(u8),
    handle: *curl.CURL,
) !void {
    log.info("Downloading metadata for ID {d}.", .{id});
    const foobar = db.one(
        bool,
        "SELECT true FROM image WHERE id = ? AND metadata IS NOT NULL;",
        .{},
        .{ .id = id },
    ) catch {
        sqliteErrorReport("SQLite error while checking for metadata precence.", db);
        return error.GO_ON;
    };
    if (foobar) |_| {
        log.info("Metadata for ID {d} already acquired. Use -u to replace.", .{id});
        return;
    }
    _ = try std.fmt.bufPrintZ(
        urlbuf[0..],
        api_base ++ "/images/{d}",
        .{id},
    );
    easyFetch(handle, &urlbuf, resp) catch {
        log.info("Failed to download metadata for ID {d}.", .{id});
        return error.FATAL;
    };
    const valid = std.json.validate(resp.items);

    if (valid) {
        try db.exec("BEGIN IMMEDIATE;", .{}, .{});
        errdefer db.exec("ROLLBACK;", .{}, .{}) catch {};
        db.exec(
            \\INSERT OR ROLLBACK
            \\  INTO
            \\    image (id, metadata)
            \\    VALUES (?, ?)
            \\  ON CONFLICT (id)
            \\    DO UPDATE
            \\    SET metadata=excluded.metadata;
        , .{}, .{ .id = id, .metadata = resp.items }) catch {
            sqliteErrorReport("Couldn't add metadata for ID {d} to database.", db);
            return error.GO_ON;
        };
        hashit(resp.items) catch |err| {
            log.err("Couldn't hash metadata for ID {d}: {s}", .{ id, err });
            return error.GO_ON;
        };
        db.exec(
            "UPDATE OR ROLLBACK image SET hash_meta = ? WHERE id = ?",
            .{},
            .{ hash_buf2[0..], id },
        ) catch {
            sqliteErrorReport("Couldn't set metadata hash", db);
            return error.GO_ON;
        };
        db.exec("COMMIT", .{}, .{}) catch {
            sqliteErrorReport("FATAL: couldn't commit database", db);
            return error.FATAL;
        };
    } else {
        log.err("Invalid metadata for ID {d}", .{id});
        return error.FATAL;
    }
}

fn getImage(
    db: *sqlite.Db,
    id: u64,
    resp: *std.ArrayList(u8),
    alloc: *std.mem.Allocator,
    handle: *curl.CURL,
) !void {
    log.info("Downloading image and thumbnail for ID {d}.", .{id});
    const foobar = db.oneAlloc(
        struct {
            full_url: ?[:0]u8,
            thumb_url: ?[:0]u8,
        },
        alloc,
        "SELECT full_url, thumb_url FROM image WHERE id = ?",
        .{},
        .{ .id = id },
    ) catch {
        sqliteErrorReport("SQLite error while getting image URLs", db);
        return error.GO_ON;
    };
    if (foobar) |res| {
        if (res.full_url) |url| blk: {
            defer alloc.free(url);
            const skipper = db.one(bool,
                \\SELECT true FROM image
                \\  WHERE id = ? AND image IS NOT NULL;
            , .{}, .{id}) catch {
                sqliteErrorReport("SQLite error while checking if image is already downloaded", db);
                return error.GO_ON;
            };
            if (skipper) |_| {
                log.info("Image for ID {d} already downloaded.", .{id});
                break :blk;
            }
            easyFetch(handle, url, resp) catch {
                log.info("Failed to download fullsize image for ID {d}", .{id});
                return error.FATAL;
            };
            try db.exec("BEGIN IMMEDIATE;", .{}, .{});
            errdefer db.exec("ROLLBACK;", .{}, .{}) catch {};
            db.exec(
                "UPDATE OR ROLLBACK image SET image = ? WHERE id = ?",
                .{},
                .{
                    .image = resp.items,
                    .id = id,
                },
            ) catch {
                sqliteErrorReport("Couldn't add image to DB.", db);
                return error.GO_ON;
            };
            hashit(resp.items) catch |err| {
                log.err("Couldn't hash image for ID {d}: {s}", .{ id, err });
                return error.GO_ON;
            };
            db.exec(
                "UPDATE OR ROLLBACK image SET hash_full = ? WHERE id = ?",
                .{},
                .{ hash_buf2[0..], id },
            ) catch {
                sqliteErrorReport("Couldn't set iamge hash", db);
                return error.GO_ON;
            };
            db.exec("COMMIT", .{}, .{}) catch {
                sqliteErrorReport("FATAL: couldn't commit database", db);
                return error.FATAL;
            };
            resp.clearRetainingCapacity();
            std.mem.set(u8, hash_buf[0..], 0);
            std.mem.set(u8, hash_buf2[0..], 0);
        }
        if (res.thumb_url) |url| blk: {
            defer alloc.free(url);
            const skipper = db.one(bool,
                \\SELECT true FROM image
                \\  WHERE id = ? AND thumb IS NOT NULL;
            , .{}, .{id}) catch {
                sqliteErrorReport("SQLite error while checking if thumb is already downloaded", db);
                return error.GO_ON;
            };
            if (skipper) |_| {
                log.info("Thumb for ID {d} already downloaded.", .{id});
                break :blk;
            }
            easyFetch(handle, url, resp) catch {
                log.info("Failed to download thumbnail image for ID {d}", .{id});
                return error.GO_ON;
            };
            try db.exec("BEGIN IMMEDIATE;", .{}, .{});
            errdefer db.exec("ROLLBACK;", .{}, .{}) catch {};
            db.exec(
                "UPDATE OR ROLLBACK image SET thumb = ? WHERE id = ?",
                .{},
                .{
                    .thumb = resp.items,
                    .id = id,
                },
            ) catch {
                sqliteErrorReport("Couldn't add thumb to DB", db);
                return error.GO_ON;
            };
            hashit(resp.items) catch |err| {
                log.err("Couldn't hash thumb for ID {d}: {s}", .{ id, err });
                return error.GO_ON;
            };
            db.exec(
                "UPDATE OR ROLLBACK image SET hash_thumb = ? WHERE id = ?",
                .{},
                .{ hash_buf2[0..], id },
            ) catch {
                sqliteErrorReport("Couldn't add thumb hash", db);
                return error.GO_ON;
            };
            db.exec("COMMIT", .{}, .{}) catch {
                sqliteErrorReport("FATAL: couldn't commit database", db);
                return error.FATAL;
            };
        }
    } else {
        log.err("No metadata for id {d} available", .{id});
        return;
    }
}

fn extractImage(db: *sqlite.Db, id: u64, alloc: *std.mem.Allocator) !void {
    log.info("Extracting image for ID {d}.", .{id});
    const foo = db.oneAlloc(
        struct {
            image: ?[:0]u8,
            extension: ?[:0]u8,
        },
        alloc,
        "SELECT image, extension FROM image WHERE id = ?",
        .{},
        .{ .id = id },
    ) catch {
        sqliteErrorReport("SQLite error while reading image", db);
        return error.GO_ON;
    };
    defer {
        if (foo) |f| {
            if (f.image) |i| {
                alloc.free(i);
            }
            if (f.extension) |e| {
                alloc.free(e);
            }
        }
    }
    if (foo) |res| {
        const bar = comptime @as([]const u8, "unknown");
        const baz = if (res.extension) |e| e else bar;
        var buf = [_]u8{0} ** 64;
        const buf2 = try std.fmt.bufPrint(
            buf[0..],
            "{d:0>10}.{s}",
            .{
                id,
                baz,
            },
        );
        if (res.image) |image| {
            var dir = try std.fs.cwd().makeOpenPath("images", .{
                .access_sub_paths = true,
            });
            var file = try dir.createFile(
                buf2,
                .{
                    .read = false,
                    .truncate = true,
                },
            );
            defer file.close();
            try file.writeAll(image);
            log.info("Extracted image for ID {d}.", .{id});
        } else {
            log.info("No image data for ID {d}.", .{id});
        }
    }
}

fn easyFetch(handle: *curl.CURL, url: [*:0]const u8, resp: *std.ArrayList(u8)) !void {
    if (fetch_wait > 0) {
        if (fetch_timer) |*timer| {
            const cur = timer.read() / (1000 * 1000);
            if (cur < fetch_wait) {
                std.time.sleep((fetch_wait - cur) * 1000 * 1000);
            }
            timer.reset();
        } else {
            fetch_timer = try std.time.Timer.start();
        }
    }
    var ret = curl.curl_easy_setopt(handle, curl.CURLOPT_URL, url);
    if (ret != curl.CURLE_OK) {
        curlErrorReport("cURL set url:", ret);
        return error.FUCK;
    }
    ret = curl.curl_easy_setopt(handle, curl.CURLOPT_WRITEFUNCTION, writeToArrayListCallback);
    if (ret != curl.CURLE_OK) {
        curlErrorReport("cURL set writefunction:", ret);
        return error.FUCK;
    }
    ret = curl.curl_easy_setopt(handle, curl.CURLOPT_WRITEDATA, resp);
    if (ret != curl.CURLE_OK) {
        curlErrorReport("cURL set writedata:", ret);
        return error.FUCK;
    }
    ret = curl.curl_easy_setopt(handle, curl.CURLOPT_USERAGENT, "Derpiloader 0.1 (linux)");
    if (ret != curl.CURLE_OK) {
        curlErrorReport("cURL set user agent:", ret);
        return error.FUCK;
    }
    ret = curl.curl_easy_perform(handle);
    if (ret != curl.CURLE_OK) {
        curlErrorReport("cURL perform:", ret);
        return error.FUCK;
    }

    log.info("Got {d} bytes", .{resp.items.len});
}

fn writeToArrayListCallback(
    data: *c_void,
    size: c_uint,
    nmemb: c_uint,
    user_data: *c_void,
) callconv(.C) c_uint {
    var buffer = @intToPtr(*std.ArrayList(u8), @ptrToInt(user_data));
    var typed_data = @intToPtr([*]u8, @ptrToInt(data));
    buffer.appendSlice(typed_data[0 .. nmemb * size]) catch return 0;
    return nmemb * size;
}