const std = @import("std");
const types = @import("../weather/types.zig");

pub fn render(allocator: std.mem.Allocator, data: types.WeatherData, format: []const u8, use_imperial: bool) ![]const u8 {
    if (std.mem.eql(u8, format, "1")) {
        const temp = if (use_imperial) data.current.temp_f else data.current.temp_c;
        const unit = if (use_imperial) "°F" else "°C";
        return std.fmt.allocPrint(allocator, "{s}: {s} {d:.0}{s}", .{
            data.location,
            getConditionEmoji(data.current.weather_code),
            temp,
            unit,
        });
    } else if (std.mem.eql(u8, format, "2")) {
        const temp = if (use_imperial) data.current.temp_f else data.current.temp_c;
        const unit = if (use_imperial) "°F" else "°C";
        const wind = if (use_imperial) data.current.wind_kph * 0.621371 else data.current.wind_kph;
        const wind_unit = if (use_imperial) "mph" else "km/h";
        return std.fmt.allocPrint(allocator, "{s}: {s} {d:.0}{s} {s}{s}{d:.0}{s}", .{
            data.location,
            getConditionEmoji(data.current.weather_code),
            temp,
            unit,
            "🌬️",
            data.current.wind_dir,
            wind,
            wind_unit,
        });
    } else if (std.mem.eql(u8, format, "3")) {
        const temp = if (use_imperial) data.current.temp_f else data.current.temp_c;
        const unit = if (use_imperial) "°F" else "°C";
        const wind = if (use_imperial) data.current.wind_kph * 0.621371 else data.current.wind_kph;
        const wind_unit = if (use_imperial) "mph" else "km/h";
        return std.fmt.allocPrint(allocator, "{s}: {s} {d:.0}{s} {s}{s}{d:.0}{s} {s}{d}%%", .{
            data.location,
            getConditionEmoji(data.current.weather_code),
            temp,
            unit,
            "🌬️",
            data.current.wind_dir,
            wind,
            wind_unit,
            "💧",
            data.current.humidity,
        });
    } else if (std.mem.eql(u8, format, "4")) {
        const temp = if (use_imperial) data.current.temp_f else data.current.temp_c;
        const unit = if (use_imperial) "°F" else "°C";
        const wind = if (use_imperial) data.current.wind_kph * 0.621371 else data.current.wind_kph;
        const wind_unit = if (use_imperial) "mph" else "km/h";
        return std.fmt.allocPrint(allocator, "{s}: {s} {d:.0}{s} {s}{s}{d:.0}{s} {s}{d}%% {s}", .{
            data.location,
            getConditionEmoji(data.current.weather_code),
            temp,
            unit,
            "🌬️",
            data.current.wind_dir,
            wind,
            wind_unit,
            "💧",
            data.current.humidity,
            "☀️",
        });
    } else {
        return renderCustom(allocator, data, format, use_imperial);
    }
}

fn renderCustom(allocator: std.mem.Allocator, data: types.WeatherData, format: []const u8, use_imperial: bool) ![]const u8 {
    var output: std.ArrayList(u8) = .empty;
    errdefer output.deinit(allocator);

    var i: usize = 0;
    while (i < format.len) {
        if (format[i] == '%' and i + 1 < format.len) {
            const code = format[i + 1];
            switch (code) {
                'c' => try output.appendSlice(allocator, getConditionEmoji(data.current.weather_code)),
                'C' => try output.appendSlice(allocator, data.current.condition),
                'h' => try output.writer(allocator).print("{d}", .{data.current.humidity}),
                't' => {
                    const temp = if (use_imperial) data.current.temp_f else data.current.temp_c;
                    try output.writer(allocator).print("{d:.0}", .{temp});
                },
                'f' => {
                    const temp = if (use_imperial) data.current.temp_f else data.current.temp_c;
                    try output.writer(allocator).print("{d:.0}", .{temp});
                },
                'w' => {
                    const wind = if (use_imperial) data.current.wind_kph * 0.621371 else data.current.wind_kph;
                    const wind_unit = if (use_imperial) "mph" else "km/h";
                    try output.writer(allocator).print("{s}{d:.0}{s}", .{ data.current.wind_dir, wind, wind_unit });
                },
                'l' => try output.appendSlice(allocator, data.location),
                'p' => {
                    const precip = if (use_imperial) data.current.precip_mm * 0.0393701 else data.current.precip_mm;
                    try output.writer(allocator).print("{d:.1}", .{precip});
                },
                'P' => {
                    const pressure = if (use_imperial) data.current.pressure_mb * 0.02953 else data.current.pressure_mb;
                    try output.writer(allocator).print("{d:.0}", .{pressure});
                },
                '%' => try output.append(allocator, '%'),
                else => {
                    try output.append(allocator, '%');
                    try output.append(allocator, code);
                },
            }
            i += 2;
        } else {
            try output.append(allocator, format[i]);
            i += 1;
        }
    }

    return output.toOwnedSlice(allocator);
}

fn getConditionEmoji(code: types.WeatherCode) []const u8 {
    return switch (@intFromEnum(code)) {
        800 => "☀️", // Clear
        801, 802 => "⛅️", // Few/scattered clouds
        803, 804 => "☁️", // Broken/overcast clouds
        701, 741 => "🌁", // Mist/fog (alternatively, maybe 🌫️ or 🌫 is better)
        300...321 => "🌦", // Drizzle
        500...531 => "🌧️", // Rain
        200...232 => "⛈️", // Thunderstorm
        611...616 => "❄️", // Sleet/freezing (check before snow)
        600...610, 617...622 => "🌨️", // Snow
        else => "🌡️",
    };
}

test "format 1" {
    const data = types.WeatherData{
        .location = "London",
        .current = .{
            .temp_c = 15.0,
            .temp_f = 59.0,
            .condition = "Clear",
            .weather_code = .clear,
            .humidity = 65,
            .wind_kph = 10.0,
            .wind_dir = "N",
            .pressure_mb = 1013.0,
            .precip_mm = 0.0,
        },
        .forecast = &.{},
        .allocator = std.testing.allocator,
    };

    const output = try render(std.testing.allocator, data, "1", false);
    defer std.testing.allocator.free(output);

    try std.testing.expectEqualStrings("London: ☀️ 15°C", output);
}

test "custom format" {
    const data = types.WeatherData{
        .location = "London",
        .current = .{
            .temp_c = 15.0,
            .temp_f = 59.0,
            .condition = "Clear",
            .weather_code = .clear,
            .humidity = 65,
            .wind_kph = 10.0,
            .wind_dir = "N",
            .pressure_mb = 1013.0,
            .precip_mm = 0.0,
        },
        .forecast = &.{},
        .allocator = std.testing.allocator,
    };

    const output = try render(std.testing.allocator, data, "%l: %c %t°C", false);
    defer std.testing.allocator.free(output);

    try std.testing.expectEqualStrings("London: ☀️ 15°C", output);
}

test "format 2 with imperial units" {
    const data = types.WeatherData{
        .location = "Portland",
        .current = .{
            .temp_c = 10.0,
            .temp_f = 50.0,
            .condition = "Cloudy",
            .weather_code = .clouds_overcast,
            .humidity = 70,
            .wind_kph = 20.0,
            .wind_dir = "SE",
            .pressure_mb = 1013.0,
            .precip_mm = 0.0,
        },
        .forecast = &.{},
        .allocator = std.testing.allocator,
    };

    const output = try render(std.testing.allocator, data, "2", true);
    defer std.testing.allocator.free(output);

    try std.testing.expectEqualStrings("Portland: ☁️ 50°F 🌬️SE12mph", output);
}