use std::path::PathBuf;

use roc_collections::MutMap;
use roc_module::symbol::{Interns, ModuleId};
use roc_problem::can::Problem;
use roc_region::all::LineInfo;
use roc_solve_problem::TypeError;

use crate::report::ANSI_STYLE_CODES;

#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
pub struct Problems {
    pub fatally_errored: bool,
    pub errors: usize,
    pub warnings: usize,
}

impl Problems {
    pub fn exit_code(&self) -> i32 {
        // 0 means no problems, 1 means errors, 2 means warnings
        if self.errors > 0 {
            1
        } else if self.warnings > 0 {
            2
        } else {
            0
        }
    }

    // prints e.g. `1 error and 0 warnings found in 63 ms.`
    pub fn print_error_warning_count(&self, total_time: std::time::Duration) {
        const GREEN: &str = ANSI_STYLE_CODES.green;
        const YELLOW: &str = ANSI_STYLE_CODES.yellow;
        const RESET: &str = ANSI_STYLE_CODES.reset;

        println!(
            "{}{}{} {} and {}{}{} {} found in {} ms",
            match self.errors {
                0 => GREEN,
                _ => YELLOW,
            },
            self.errors,
            RESET,
            match self.errors {
                1 => "error",
                _ => "errors",
            },
            match self.warnings {
                0 => GREEN,
                _ => YELLOW,
            },
            self.warnings,
            RESET,
            match self.warnings {
                1 => "warning",
                _ => "warnings",
            },
            total_time.as_millis()
        );
    }
}

pub fn report_problems(
    sources: &MutMap<ModuleId, (PathBuf, Box<str>)>,
    interns: &Interns,
    can_problems: &mut MutMap<ModuleId, Vec<roc_problem::can::Problem>>,
    type_problems: &mut MutMap<ModuleId, Vec<TypeError>>,
) -> Problems {
    use crate::report::{can_problem, type_problem, Report, RocDocAllocator, DEFAULT_PALETTE};
    use roc_problem::Severity::*;

    let palette = DEFAULT_PALETTE;
    let mut total_problems = 0;

    for problems in can_problems.values() {
        total_problems += problems.len();
    }

    for problems in type_problems.values() {
        total_problems += problems.len();
    }

    // This will often over-allocate total memory, but it means we definitely
    // never need to re-allocate either the warnings or the errors vec!
    let mut warnings = Vec::with_capacity(total_problems);
    let mut errors = Vec::with_capacity(total_problems);
    let mut fatally_errored = false;

    for (home, (module_path, src)) in sources.iter() {
        let mut src_lines: Vec<&str> = Vec::new();

        src_lines.extend(src.split('\n'));

        let lines = LineInfo::new(&src_lines.join("\n"));

        // Report parsing and canonicalization problems
        let alloc = RocDocAllocator::new(&src_lines, *home, interns);

        let problems = type_problems.remove(home).unwrap_or_default();

        for problem in problems {
            if let Some(report) = type_problem(&alloc, &lines, module_path.clone(), problem) {
                let severity = report.severity;
                let mut buf = String::new();

                report.render_color_terminal(&mut buf, &alloc, &palette);

                match severity {
                    Warning => {
                        warnings.push(buf);
                    }
                    RuntimeError => {
                        errors.push(buf);
                    }
                    Fatal => {
                        fatally_errored = true;
                        errors.push(buf);
                    }
                }
            }
        }

        // Shadowing errors often cause cryptic type errors. To make it easy to spot the root cause,
        // we print the shadowing errors last.
        let problems = can_problems.remove(home).unwrap_or_default();
        let (shadowing_errs, mut ordered): (Vec<Problem>, Vec<Problem>) =
            problems.into_iter().partition(|p| {
                matches!(
                    p,
                    Problem::Shadowing {
                        original_region: _,
                        shadow: _,
                        kind: _,
                    }
                )
            });
        ordered.extend(shadowing_errs);

        for problem in ordered.into_iter() {
            let report = can_problem(&alloc, &lines, module_path.clone(), problem);
            let severity = report.severity;
            let mut buf = String::new();

            report.render_color_terminal(&mut buf, &alloc, &palette);

            match severity {
                Warning => {
                    warnings.push(buf);
                }
                RuntimeError => {
                    errors.push(buf);
                }
                Fatal => {
                    fatally_errored = true;
                    errors.push(buf);
                }
            }
        }
    }

    debug_assert!(can_problems.is_empty() && type_problems.is_empty(), "After reporting problems, there were {:?} can_problems and {:?} type_problems that could not be reported because they did not have corresponding entries in `sources`.", can_problems.len(), type_problems.len());
    debug_assert_eq!(errors.len() + warnings.len(), total_problems);

    let problems_reported;

    // Only print warnings if there are no errors
    if errors.is_empty() {
        problems_reported = warnings.len();

        for warning in warnings.iter() {
            println!("\n{warning}\n");
        }
    } else {
        problems_reported = errors.len();

        for error in errors.iter() {
            println!("\n{error}\n");
        }
    }

    // If we printed any problems, print a horizontal rule at the end,
    // and then clear any ANSI escape codes (e.g. colors) we've used.
    //
    // The horizontal rule is nice when running the program right after
    // compiling it, as it lets you clearly see where the compiler
    // errors/warnings end and the program output begins.
    if problems_reported > 0 {
        println!("{}\u{001B}[0m\n", Report::horizontal_rule(&palette));
    }

    Problems {
        fatally_errored,
        errors: errors.len(),
        warnings: warnings.len(),
    }
}