//! `IntSpan` handles of sets containing integer spans.
//!
//! # SYNOPSIS
//!
//! ```
//! use intspan::IntSpan;
//!
//! let mut set = IntSpan::new();
//! for i in vec![1, 2, 3, 5, 7, 9] {
//!     set.add_n(i);
//! }
//! set.add_pair(100, 10000);
//! set.remove_n(1000);
//!
//! let expected = "1-3,5,7,9,100-999,1001-10000";
//! # assert_eq!(set.to_string(), expected);
//! # assert_eq!(set.cardinality(), 9906);
//! # assert_eq!(set.is_empty(), false);
//! # assert_eq!(set.is_universal(), false);
//! # assert_eq!(set.is_infinite(), false);
//! # assert_eq!(set.is_finite(), true);
//! # assert_eq!(set.is_pos_inf(), false);
//! # assert_eq!(set.is_neg_inf(), false);
//! ```
//!
//! ```
//! # use intspan::IntSpan;
//! let set = IntSpan::from("1-3,5,7,9,100-999,1001-10000");
//! # assert_eq!(set.to_string(), "1-3,5,7,9,100-999,1001-10000");
//! # assert_eq!(set.cardinality(), 9906);
//! ```
//!
//! # DESCRIPTION
//!
//! `IntSpan` represents sets of integers as a number of inclusive ranges, for example
//! `1-10,19-23,45-48`. Because many of its operations involve linear searches of the list of ranges its
//! overall performance tends to be proportional to the number of distinct ranges. This is fine for
//! small sets but suffers compared to other possible set representations (bit vectors, hash keys) when
//! the number of ranges grows large.
//!
//! This module also represents sets as ranges of values but stores those ranges in order and uses a
//! binary search for many internal operations so that overall performance tends towards O log N where N
//! is the number of ranges.
//!
//! The internal representation used by this module is extremely simple: a set is represented as a list
//! of integers. Integers in even numbered positions (0, 2, 4 etc) represent the start of a run of
//! numbers while those in odd numbered positions represent the ends of runs. As an example the set (1,
//! 3-7, 9, 11, 12) would be represented internally as (1, 2, 3, 8, 11, 13).
//!
//! Sets may be infinite - assuming you're prepared to accept that infinity is actually no more than a
//! fairly large integer. Specifically the constants `neg_inf` and `pos_inf` are defined to be (-2^31+1)
//! and (2^31-2) respectively. To create an infinite set invert an empty one:
//!
//! ```
//! # use intspan::IntSpan;
//! let mut set = IntSpan::new();
//! set.invert();
//! # let expected = format!("{}-{}", set.get_neg_inf(), set.get_pos_inf());
//! # assert_eq!(set.to_string(), expected);
//! # assert_eq!(set.is_empty(), false);
//! # assert_eq!(set.is_universal(), true);
//! # assert_eq!(set.is_infinite(), true);
//! # assert_eq!(set.is_finite(), false);
//! # assert_eq!(set.is_pos_inf(), true);
//! # assert_eq!(set.is_neg_inf(), true);
//! ```
//!
//! Sets need only be bounded in one direction - for example this is the set of all positive integers
//! (assuming you accept the slightly feeble definition of infinity we're using):
//!
//! ```
//! # use intspan::IntSpan;
//! let mut set = IntSpan::new();
//! set.add_pair(1, set.get_pos_inf());
//! # let expected = format!("{}-{}", 1, set.get_pos_inf());
//! # assert_eq!(set.to_string(), expected);
//! # assert_eq!(set.is_empty(), false);
//! # assert_eq!(set.is_universal(), false);
//! # assert_eq!(set.is_infinite(), true);
//! # assert_eq!(set.is_finite(), false);
//! # assert_eq!(set.is_pos_inf(), true);
//! # assert_eq!(set.is_neg_inf(), false);
//! ```
//!
//! This Rust crate is ported from the Java class `jintspan` and the Perl module `AlignDB::IntSpan`,
//! which contains many codes from `Set::IntSpan`, `Set::IntSpan::Fast` and `Set::IntSpan::Island`.
//!

use std::fmt;
use std::vec::Vec;

#[derive(Default)]
pub struct IntSpan {
    edges: Vec<i32>,
    pos_inf: i32,
    neg_inf: i32,
    empty_string: String,
}

//----------------------------------------------------------
// Set contents
//----------------------------------------------------------

impl IntSpan {
    pub fn new() -> Self {
        IntSpan {
            edges: Vec::new(),
            pos_inf: 2_147_483_647 - 1, // INT_MAX - 1, Real Largest int is POS_INF - 1
            neg_inf: -2_147_483_648 + 1, // INT_MIN + 1
            empty_string: "-".to_string(),
        }
    }

    pub fn from<S>(runlist: S) -> Self
    where
        S: Into<String>,
    {
        let s = runlist.into();

        let mut new = Self::new();
        new.add_runlist(s);

        new
    }

    pub fn get_neg_inf(&self) -> i32 {
        self.neg_inf.clone()
    }

    pub fn get_pos_inf(&self) -> i32 {
        self.pos_inf.clone() - 1
    }

    pub fn clear(&mut self) {
        self.edges.clear();
    }

    pub fn edge_size(&self) -> usize {
        self.edges.len()
    }

    pub fn span_size(&self) -> usize {
        self.edge_size() / 2
    }

    pub fn to_string(&self) -> String {
        if self.is_empty() {
            return self.empty_string.clone();
        }

        let mut runlist = "".to_string();

        for i in 0..self.span_size() {
            let lower = *self.edges.get(i * 2).unwrap();
            let upper = *self.edges.get(i * 2 + 1).unwrap() - 1;

            let mut buf = "".to_string();
            if i != 0 {
                buf.push_str(",");
            }

            if lower == upper {
                buf.push_str(lower.to_string().as_str());
            } else {
                buf.push_str(format!("{}-{}", lower, upper).as_str());
            }

            runlist.push_str(buf.as_str());
        }

        runlist
    }

    pub fn to_vec(&self) -> Vec<i32> {
        let mut elements: Vec<i32> = Vec::new();

        for i in 0..self.span_size() {
            let lower = *self.edges.get(i * 2).unwrap();
            let upper = *self.edges.get(i * 2 + 1).unwrap() - 1;

            let span_len = upper - lower + 1;
            for j in 0..span_len {
                elements.push(lower + j);
            }
        }

        elements
    }

    pub fn ranges(&self) -> Vec<i32> {
        let mut ranges: Vec<i32> = Vec::new();

        for i in 0..self.edges.len() {
            // odd index means upper
            if (i & 1) == 1 {
                ranges.push(*self.edges.get(i).unwrap() - 1);
            } else {
                ranges.push(*self.edges.get(i).unwrap());
            }
        }

        ranges
    }

    pub fn contains(&self, n: i32) -> bool {
        let pos = self.find_pos(n + 1, 0);
        (pos & 1) == 1
    }

    pub fn min(&self) -> i32 {
        if self.is_empty() {
            panic!("Can't get extrema for empty IntSpan");
        }

        *self.edges.first().unwrap()
    }

    pub fn max(&self) -> i32 {
        if self.is_empty() {
            panic!("Can't get extrema for empty IntSpan");
        }

        *self.edges.last().unwrap() - 1
    }
}

//----------------------------------------------------------
// Set cardinality
//----------------------------------------------------------
impl IntSpan {
    pub fn cardinality(&self) -> i32 {
        let mut cardinality: i32 = 0;

        if self.is_empty() {
            return cardinality;
        }

        for i in 0..self.span_size() {
            let lower = *self.edges.get(i * 2).unwrap();
            let upper = *self.edges.get(i * 2 + 1).unwrap() - 1;

            cardinality += upper - lower + 1;
        }

        cardinality
    }

    pub fn is_empty(&self) -> bool {
        self.edges.is_empty()
    }

    pub fn is_neg_inf(&self) -> bool {
        *self.edges.first().unwrap() == self.neg_inf
    }

    pub fn is_pos_inf(&self) -> bool {
        *self.edges.last().unwrap() == self.pos_inf
    }

    pub fn is_infinite(&self) -> bool {
        self.is_neg_inf() || self.is_pos_inf()
    }

    pub fn is_finite(&self) -> bool {
        !self.is_infinite()
    }

    pub fn is_universal(&self) -> bool {
        self.edge_size() == 2 && self.is_pos_inf() && self.is_neg_inf()
    }
}

//----------------------------------------------------------
// Member operations (mutate original set)
//----------------------------------------------------------
impl IntSpan {
    pub fn add_pair(&mut self, mut lower: i32, mut upper: i32) {
        if lower > upper {
            panic!("Bad order: {},{}", lower, upper)
        }

        upper += 1;

        let mut lower_pos = self.find_pos(lower, 0);
        let mut upper_pos = self.find_pos(upper + 1, lower_pos);

        if lower_pos & 1 == 1 {
            lower_pos -= 1;
            lower = *self.edges.get(lower_pos).unwrap();
        }

        if upper_pos & 1 == 1 {
            upper = *self.edges.get(upper_pos).unwrap();
            upper_pos += 1;
        }

        for _i in lower_pos..upper_pos {
            self.edges.remove(lower_pos);
        }
        self.edges.insert(lower_pos, lower);
        self.edges.insert(lower_pos + 1, upper);
    }

    pub fn add_n(&mut self, n: i32) {
        self.add_pair(n, n);
    }

    pub fn add_range(&mut self, ranges: &Vec<i32>) {
        if ranges.len() % 2 != 0 {
            panic!("Number of ranges must be even")
        }

        for i in 0..(ranges.len() / 2) {
            let lower = *ranges.get(i * 2).unwrap();
            let upper = *ranges.get(i * 2 + 1).unwrap();

            self.add_pair(lower, upper);
        }

        // CAUTIONS: can't capture bad orders
        //        // When this IntSpan is empty, just convert ranges to edges
        //        if self.is_empty() {
        //            for i in 0..ranges.len() {
        //                // odd index means upper
        //                if (i & 1) == 1 {
        //                    self.edges.push(*ranges.get(i).unwrap() + 1);
        //                } else {
        //                    self.edges.push(*ranges.get(i).unwrap());
        //                }
        //            }
        //        } else {
        //            for i in 0..(ranges.len() / 2) {
        //                let lower = *ranges.get(i * 2).unwrap();
        //                let upper = *ranges.get(i * 2 + 1).unwrap();
        //
        //                self.add_pair(lower, upper);
        //            }
        //        }
    }

    pub fn merge(&mut self, other: &Self) {
        let ranges = other.ranges();

        self.add_range(&ranges);
    }

    pub fn add_vec(&mut self, ints: &Vec<i32>) {
        let ranges = self.list_to_ranges(ints);

        self.add_range(&ranges);
    }

    // https://hermanradtke.com/2015/05/06/creating-a-rust-function-that-accepts-string-or-str.html
    pub fn add_runlist<S>(&mut self, runlist: S)
    where
        S: Into<String>,
    {
        let s = runlist.into();
        // skip empty runlist
        if !s.is_empty() && !s.eq(&self.empty_string) {
            let ranges = self.runlist_to_ranges(&s);
            self.add_range(&ranges);
        }
    }

    pub fn invert(&mut self) {
        if self.is_empty() {
            // Universal set
            self.edges.push(self.neg_inf);
            self.edges.push(self.pos_inf);
        } else {
            // Either add or remove infinity from each end. The net effect is always an even number
            // of additions and deletions

            if self.is_neg_inf() {
                self.edges.remove(0); // shift
            } else {
                self.edges.insert(0, self.neg_inf); // unshift
            }

            if self.is_pos_inf() {
                self.edges.pop(); // pop
            } else {
                self.edges.push(self.pos_inf); // push
            }
        }
    }

    pub fn remove_pair(&mut self, lower: i32, upper: i32) {
        self.invert();
        self.add_pair(lower, upper);
        self.invert();
    }

    pub fn remove_n(&mut self, n: i32) {
        self.remove_pair(n, n);
    }

    pub fn remove_range(&mut self, ranges: &Vec<i32>) {
        if ranges.len() % 2 != 0 {
            panic!("Number of ranges must be even");
        }

        self.invert();
        self.add_range(ranges);
        self.invert();
    }

    pub fn subtract(&mut self, other: &Self) {
        let ranges = other.ranges();

        self.remove_range(&ranges);
    }

    pub fn remove_vec(&mut self, ints: &Vec<i32>) {
        let ranges = self.list_to_ranges(ints);

        self.remove_range(&ranges);
    }

    pub fn remove_runlist<S>(&mut self, runlist: S)
    where
        S: Into<String>,
    {
        let s = runlist.into();
        // skip empty runlist
        if !s.is_empty() && !s.eq(&self.empty_string) {
            let ranges = self.runlist_to_ranges(&s);
            self.remove_range(&ranges);
        }
    }
}

//----------------------------------------------------------
// Set binary operations (create new set)
//----------------------------------------------------------
impl IntSpan {
    pub fn copy(&self) -> Self {
        IntSpan {
            edges: self.edges.clone(),
            pos_inf: 2_147_483_647 - 1, // INT_MAX - 1, Real Largest int is POS_INF - 1
            neg_inf: -2_147_483_648 + 1, // INT_MIN + 1
            empty_string: "-".to_string(),
        }
    }

    pub fn union(&self, other: &Self) -> Self {
        let mut new = self.copy();
        new.merge(&other);
        new
    }

    pub fn complement(&self) -> Self {
        let mut new = self.copy();
        new.invert();
        new
    }

    pub fn diff(&self, other: &Self) -> Self {
        if self.is_empty() {
            Self::new()
        } else {
            let mut new = self.copy();
            new.subtract(&other);
            new
        }
    }

    pub fn intersect(&self, other: &Self) -> Self {
        if self.is_empty() || other.is_empty() {
            Self::new()
        } else {
            let mut new = self.complement();
            new.merge(&other.complement());
            new.invert();
            new
        }
    }

    pub fn xor(&self, other: &Self) -> Self {
        let mut new = self.union(&other);
        let intersect = self.intersect(&other);
        new.subtract(&intersect);
        new
    }
}

//----------------------------------------------------------
// Set relations
//----------------------------------------------------------
impl IntSpan {
    pub fn equals(&self, other: &Self) -> bool {
        let edges = &self.edges;
        let edges_other = &other.edges;

        if edges.len() != edges_other.len() {
            return false;
        }

        for i in 0..edges.len() {
            if edges.get(i) != edges_other.get(i) {
                return false;
            }
        }

        true
    }

    pub fn subset(&self, other: &Self) -> bool {
        self.diff(&other).is_empty()
    }

    pub fn superset(&self, other: &Self) -> bool {
        other.diff(&self).is_empty()
    }
}

//----------------------------------------------------------
// Spans Ops
//----------------------------------------------------------
impl IntSpan {
    pub fn cover(&self) -> Self {
        let mut new = IntSpan::new();
        if !self.is_empty() {
            new.add_pair(self.min(), self.max());
        }
        new
    }

    pub fn holes(&self) -> Self {
        let mut new = IntSpan::new();
        if self.is_empty() || self.is_universal() {
            // empty and universal set have no holes
            return new;
        }
        let complement = self.complement();
        let mut ranges = complement.ranges();

        // Remove infinite arms of complement set
        if complement.is_neg_inf() {
            ranges.remove(0);
            ranges.remove(0);
        }
        if complement.is_pos_inf() {
            ranges.pop();
            ranges.pop();
        }

        new.add_range(&ranges);

        new
    }

    pub fn inset(&self, n: i32) -> Self {
        let mut new = IntSpan::new();

        for i in 0..self.span_size() {
            let mut lower = *self.edges.get(i * 2).unwrap();
            let mut upper = *self.edges.get(i * 2 + 1).unwrap() - 1;

            if lower != self.get_neg_inf() {
                lower += n;
            }
            if upper != self.get_pos_inf() {
                upper -= n;
            }

            if lower <= upper {
                new.add_pair(lower, upper);
            }
        }

        new
    }

    pub fn trim(&self, n: i32) -> Self {
        self.inset(n)
    }

    pub fn pad(&self, n: i32) -> Self {
        self.inset(-n)
    }

    pub fn excise(&self, min_len: i32) -> Self {
        let mut new = IntSpan::new();

        for i in 0..self.span_size() {
            let lower = *self.edges.get(i * 2).unwrap();
            let upper = *self.edges.get(i * 2 + 1).unwrap() - 1;

            let span_len = upper - lower + 1;
            if span_len >= min_len {
                new.add_pair(lower, upper);
            }
        }

        new
    }

    pub fn fill(&self, max_len: i32) -> Self {
        let mut new = self.copy();
        let holes = self.holes();

        for i in 0..holes.span_size() {
            let lower = *holes.edges.get(i * 2).unwrap();
            let upper = *holes.edges.get(i * 2 + 1).unwrap() - 1;

            let span_len = upper - lower + 1;
            if span_len <= max_len {
                new.add_pair(lower, upper);
            }
        }

        new
    }
}

//----------------------------------------------------------
// TODO: Inter-set operations
//----------------------------------------------------------

//----------------------------------------------------------
// TODO: Islands
//----------------------------------------------------------

//----------------------------------------------------------
// Aliases
//----------------------------------------------------------
impl IntSpan {
    pub fn size(&self) -> i32 {
        self.cardinality()
    }

    pub fn runlist(&self) -> String {
        self.to_string()
    }

    pub fn elements(&self) -> Vec<i32> {
        self.to_vec()
    }
}

//----------------------------------------------------------
// Private methods
//----------------------------------------------------------

impl IntSpan {
    fn find_pos(&self, val: i32, mut low: usize) -> usize {
        let mut high = self.edge_size();

        while low < high {
            let mid = (low + high) / 2;
            if val < *self.edges.get(mid).unwrap() {
                high = mid;
            } else if val > *self.edges.get(mid).unwrap() {
                low = mid + 1;
            } else {
                return mid;
            }
        }

        low
    }

    fn list_to_ranges(&self, ints: &Vec<i32>) -> Vec<i32> {
        let mut ranges: Vec<i32> = Vec::new();

        let mut ints = ints.clone();
        ints.sort_unstable();
        ints.dedup();

        let len = ints.len();
        let mut pos: usize = 0;

        while pos < len {
            let mut end = pos + 1;
            while (end < len) && (ints[end] <= ints[end - 1] + 1) {
                end += 1;
            }
            ranges.push(ints[pos]);
            ranges.push(ints[end - 1]);
            pos = end;
        }

        ranges
    }

    fn runlist_to_ranges(&self, runlist: &String) -> Vec<i32> {
        let mut ranges: Vec<i32> = Vec::new();

        let bytes = runlist.as_bytes();

        let radix = 10;
        let mut idx = 0; // index in runlist
        let len = bytes.len();

        let mut lower_is_neg = false;
        let mut upper_is_neg = false;
        let mut in_upper = false;

        while idx < len {
            let mut i = 0; // index in one run
            if *bytes.get(idx).unwrap() == b'-' {
                lower_is_neg = true;
                i += 1;
            }

            // ported from Java Integer.parseInt()
            let mut lower: i32 = 0;
            let mut upper: i32 = 0;

            while idx + i < len {
                let ch = bytes[idx + i];
                if ch >= b'0' && ch <= b'9' {
                    if !in_upper {
                        lower *= radix;
                        lower -= (ch as char).to_digit(10).unwrap() as i32;
                    } else {
                        upper *= radix;
                        upper -= (ch as char).to_digit(10).unwrap() as i32;
                    }
                } else if ch == b'-' {
                    if !in_upper {
                        in_upper = true;
                        if *bytes.get(idx + i + 1).unwrap() == b'-' {
                            upper_is_neg = true;
                        }
                    }
                } else if ch == b',' {
                    i += 1;
                    break; // end of run
                } else {
                    panic!(
                        "Number format error: {} at {} of {}",
                        ch as char,
                        idx + i,
                        runlist
                    );
                }

                i += 1;
            }

            if !in_upper {
                ranges.push(if lower_is_neg { lower } else { -lower }); // add lower
                ranges.push(if lower_is_neg { lower } else { -lower }); // add lower again
            } else {
                ranges.push(if lower_is_neg { lower } else { -lower }); // add lower
                ranges.push(if upper_is_neg { upper } else { -upper }); // add upper
            }

            // reset boolean flags
            lower_is_neg = false;
            upper_is_neg = false;
            in_upper = false;

            // start next run
            idx += i;
        }

        ranges
    }
}

impl fmt::Display for IntSpan {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", self.to_string())?;
        Ok(())
    }
}