use crate::fax::negotiate::DataRate;

#[derive(Debug, Clone)]
pub struct SpeedFallback {
    rates: Vec<DataRate>,
    current_index: usize,
}

impl Default for SpeedFallback {
    fn default() -> Self {
        Self {
            rates: vec![
                DataRate::V17_14400,
                DataRate::V17_12000,
                DataRate::V29_9600,
                DataRate::V29_7200,
                DataRate::V27ter4800,
            ],
            current_index: 0,
        }
    }
}

impl SpeedFallback {
    pub fn new() -> Self {
        Self::default()
    }

    pub fn current_rate(&self) -> DataRate {
        self.rates[self.current_index]
    }

    pub fn lower_speed(&mut self) -> Option<DataRate> {
        if self.current_index + 1 < self.rates.len() {
            self.current_index += 1;
            Some(self.rates[self.current_index])
        } else {
            None
        }
    }

    pub fn reset(&mut self) {
        self.current_index = 0;
    }

    pub fn is_min_speed(&self) -> bool {
        self.current_index == self.rates.len() - 1
    }

    pub fn set_initial_rate(&mut self, rate: DataRate) {
        for (i, r) in self.rates.iter().enumerate() {
            if *r == rate {
                self.current_index = i;
                return;
            }
        }
        self.current_index = 0;
    }
}