1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130

//! A simple logger for front end wasm web app.
//!
//! Please see [README](https://gitlab.com/limira-rs/wasm-logger/blob/master/README.md) for documentation.
#[deny(missing_docs)]
use log::{Level, Log, Metadata, Record};
use wasm_bindgen::prelude::*;
use web_sys::console;

/// Specifies what to be logged
pub struct Config {
    level: Level,
    path_prefix: Option<String>,
}

impl Config {
    /// Specify the maximum level you want to log
    pub fn new(level: Level) -> Self {
        Self {
            level,
            path_prefix: None,
        }
    }

    /// Both maximum level and path_prefix
    pub fn with_prefix(level: Level, path_prefix: &str) -> Self {
        Self {
            level,
            path_prefix: Some(path_prefix.to_string()),
        }
    }
}

/// The log styles
struct Style {
    lvl_trace: String,
    lvl_debug: String,
    lvl_info: String,
    lvl_warn: String,
    lvl_error: String,
    tgt: String,
    args: String,
}

impl Style {
    fn new() -> Style {
        let base = String::from("color: white; padding: 0 3px; background:");
        Style {
            lvl_trace: format!("{} darkgray;", base),
            lvl_debug: format!("{} darkgreen;", base),
            lvl_info: format!("{} green;", base),
            lvl_warn: format!("{} gold;", base),
            lvl_error: format!("{} red;", base),
            tgt: String::from("font-weight: bold; color: inherit"),
            args: String::from("background: inherit; color: inherit"),
        }
    }
}

/// The logger
struct WasmLogger {
    config: Config,
    style: Style,
}

impl Log for WasmLogger {
    fn enabled(&self, metadata: &Metadata<'_>) -> bool {
        if let Some(ref prefix) = self.config.path_prefix {
            metadata.target().starts_with(prefix)
        } else {
            true
        }
    }

    fn log(&self, record: &Record<'_>) {
        if self.enabled(record.metadata()) {
            let style = &self.style;
            let s = JsValue::from_str(&format!(
                "[%c{: <5}%c {}%c] {}",
                record.level(),
                record.target(),
                record.args()
            ));
            let tgt_style = JsValue::from_str(&style.tgt);
            let args_style = JsValue::from_str(&style.args);

            match record.level() {
                Level::Trace => console::debug_4(
                    &s,
                    &JsValue::from(&style.lvl_trace),
                    &tgt_style,
                    &args_style,
                ),
                Level::Debug => console::log_4(
                    &s,
                    &JsValue::from(&style.lvl_debug),
                    &tgt_style,
                    &args_style,
                ),
                Level::Info => {
                    console::info_4(&s, &JsValue::from(&style.lvl_info), &tgt_style, &args_style)
                }
                Level::Warn => {
                    console::warn_4(&s, &JsValue::from(&style.lvl_warn), &tgt_style, &args_style)
                }
                Level::Error => console::error_4(
                    &s,
                    &JsValue::from(&style.lvl_error),
                    &tgt_style,
                    &args_style,
                ),
            }
        }
    }

    fn flush(&self) {}
}

/// Initialize the logger which the given config. If failed, it will log a message to the the browser console.
pub fn init(config: Config) {
    let max_level = config.level;
    let wl = WasmLogger {
        config,
        style: Style::new(),
    };

    match log::set_boxed_logger(Box::new(wl)) {
        Ok(_) => log::set_max_level(max_level.to_level_filter()),
        Err(e) => console::error_1(&JsValue::from(e.to_string())),
    }
}