use serde::{Deserialize, Serialize};

/// Domain, in sectors.
/// Requires sector_size to be provided elsewhere for conversion to bytes.
#[derive(Clone, Copy, Debug, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
pub struct Domain {
    pub start: usize,
    pub end: usize,
}

impl Default for Domain {
    fn default() -> Self {
        Domain { start: 0, end: 1 }
    }
}

impl Domain {
    /// Return length of domain in sectors.
    pub fn len(self) -> usize {
        self.end - self.start
    }

    /// Returns the type of overlap between this domain and another.
    pub fn overlap(&self, other: Domain) -> DomainOverlap {
        if self.end <= other.start || other.end <= self.start {
            // Cases 7, 8, 12, and 13 of map::tests::test_update
            DomainOverlap::None
        } else if other.start >= self.start && other.end <= self.end {
            // Cases 3, 5, 9, and 11 of map::tests::test_update
            DomainOverlap::SelfEngulfsOther
        } else if other.start <= self.start && other.end >= self.end {
            // Cases 4, 6, and 10 of map::tests::test_update
            DomainOverlap::OtherEngulfsSelf
        } else if self.start < other.start {
            // Case 1 of map::tests::test_update
            DomainOverlap::OtherOverlapsEnd
        } else {
            // Case 2 of map::tests::test_update
            DomainOverlap::OtherOverlapsStart
        }
    }
}

pub enum DomainOverlap {
    None,
    SelfEngulfsOther,
    OtherEngulfsSelf,
    OtherOverlapsStart,
    OtherOverlapsEnd,
}

#[cfg(test)]
mod tests {
    use super::*;
}