use super::*;
use crate::ast_util::scopes::ScopeManager;
use std::{collections::HashSet, convert::Infallible};

use full_moon::ast::Ast;

fn is_global(name: &str, roblox: bool) -> bool {
    (roblox && name == "shared") || name == "_G"
}

pub struct GlobalLint;

impl Rule for GlobalLint {
    type Config = ();
    type Error = Infallible;

    fn new(_: Self::Config) -> Result<Self, Self::Error> {
        Ok(GlobalLint)
    }

    fn pass(&self, ast: &Ast, context: &Context) -> Vec<Diagnostic> {
        let scope_manager = ScopeManager::new(ast);
        let mut checked = HashSet::new(); // TODO: Fix ScopeManager having duplicate references

        scope_manager
            .references
            .iter()
            .filter(|(_, reference)| {
                if !checked.contains(&reference.identifier) {
                    checked.insert(reference.identifier);
                    is_global(&reference.name, context.is_roblox()) && reference.resolved.is_none()
                } else {
                    false
                }
            })
            .map(|(_, reference)| {
                Diagnostic::new(
                    "global_usage",
                    format!(
                        "use of `{}` is not allowed, structure your code in a more idiomatic way",
                        reference.name
                    ),
                    Label::new(reference.identifier),
                )
            })
            .collect()
    }

    fn severity(&self) -> Severity {
        Severity::Warning
    }

    fn rule_type(&self) -> RuleType {
        RuleType::Complexity
    }
}

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

    #[test]
    fn test_global_usage() {
        test_lint(GlobalLint::new(()).unwrap(), "global_usage", "global_usage");
    }
}