const std = @import("std");
const httpz = @import("../.deps/http.zig/src/httpz.zig");
const models = @import("../db/models.zig");
const ztime = @import("../.deps/time.zig");
const utils = @import("../utils.zig");

const handler = @import("../http_handler.zig");

pub fn fetchTransFromDb(allocator: std.mem.Allocator, budget_id: u32) !?[]models.Transaction {
    var db = handler.getDb();
    const now = ztime.DateTime.now();
    const beginningOfMonth = ztime.DateTime.init(now.years, now.months, 0, 0, 0, 0);

    comptime {
        if (!std.mem.eql(u8, @typeInfo(models.Transaction).Struct.fields[7].name, "date")) {
            return error{TransactionModelError};
        }
    }
    const transactions = try db.selectAllWhere(
        models.Transaction,
        allocator,
        "WHERE budget_id = ? AND date > ? AND hide = ?",
        .{ .budget_id = budget_id, .date = beginningOfMonth.toUnixMilli(), .hide = 0 },
        null,
    );
    return transactions;
}

pub fn getTransactions(req: *httpz.Request, res: *httpz.Response) !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    const allocator = gpa.allocator();

    const budget_id_str = req.param("budget_id");
    if (budget_id_str == null) {
        handler.returnError("Bad request", 400, res);
        return;
    }
    const budget_id = std.fmt.parseInt(u32, budget_id_str.?, 0) catch {
        handler.returnError("Bad request", 400, res);
        return;
    };

    const transactions = try fetchTransFromDb(allocator, budget_id);

    if (transactions == null) {
        res.status = 200;
        res.body = "";
        return;
    }
    // std.debug.print("Transactions got:\n", .{});
    // for (transactions.?) |transaction| {
    //     std.debug.print("\t{any}\n", .{transaction});
    // }
    try handler.returnData(.{ .transactions = transactions.? }, res);
}

pub fn putTransaction(req: *httpz.Request, res: *httpz.Response) !void {
    var db = handler.getDb();
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    const allocator = gpa.allocator();

    const body_data = req.json(models.Transaction) catch |err| {
        std.debug.print("Malformed body: {any}\n", .{err});
        handler.returnError("Bad request: Malformed Body", 400, res);
        return;
    };
    if (body_data == null) {
        handler.returnError("Bad request: No Data", 400, res);
        return;
    }
    var transaction = body_data.?;

    // Add Transaction
    const now = @intCast(u64, std.time.milliTimestamp());
    // Update existing Transaction
    transaction.updated_at = now;
    try db.updateById(models.Transaction, transaction);

    const query = models.createSelectOnIdQuery(models.Transaction);
    const updated_trans = try db.selectOne(models.Transaction, allocator, query, .{ .id = transaction.id });
    if (updated_trans) |trans| {
        try handler.returnData(trans, res);
    } else {
        handler.returnError("Internal Server Error", 500, res);
    }
    return;
}

const TransPostReq = struct {
    id: ?u32,
    amount: f64,
    type: []const u8,
    memo: ?[]const u8,
    budget_id: u32,
    added_by_user_id: u32,
    budget_category_id: ?u32,
    date: u64,
    created_at: ?u64,
    updated_at: ?u64,
    hide: u8,
};

pub fn postTransaction(req: *httpz.Request, res: *httpz.Response) !void {
    comptime {
        const putReqLen = @typeInfo(TransPostReq).Struct.fields.len;
        const transLen = @typeInfo(models.Transaction).Struct.fields.len;
        if (putReqLen != transLen) {
            @compileError(std.fmt.comptimePrint("TransactionPutReq does not equal Transaction model struct, fields inconsistent", .{}));
        }
    }
    var db = handler.getDb();
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    const allocator = gpa.allocator();

    const body_data = req.json(TransPostReq) catch |err| {
        std.debug.print("Malformed body: {any}\n", .{err});
        handler.returnError("Bad request: Malformed Body", 400, res);
        return;
    };
    if (body_data == null) {
        handler.returnError("Bad request: No Data", 400, res);
        return;
    }
    var body = body_data.?;

    if (body.id != null) {
        handler.returnError("Bad request: ID", 400, res);
        return;
    }

    const now = @intCast(u64, std.time.milliTimestamp());
    body.created_at = now;
    body.updated_at = now;

    try db.insert(models.Transaction, utils.removeStructFields(body, &[_]u8{0}));

    // Get new Transaction
    const query = try models.createSelectOnFieldQuery(models.Transaction, null, "created_at", "=");
    const updated_tran = try db.selectOne(models.Transaction, allocator, query, .{ .created_at = body.created_at });
    if (updated_tran) |tran| {
        try handler.returnData(tran, res);
    } else {
        handler.returnError("Internal Server Error", 500, res);
    }
    return;
}