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use std::collections::HashMap;

use crate::diagnostics::{ApolloDiagnostic, DiagnosticData, Label};
use crate::validation::{NodeLocation, ValidationDatabase};
use crate::{ast, Node};

pub(crate) fn validate_arguments(
    db: &dyn ValidationDatabase,
    arguments: &[Node<ast::Argument>],
) -> Vec<ApolloDiagnostic> {
    let mut diagnostics = Vec::new();
    let mut seen = HashMap::<_, Option<NodeLocation>>::new();

    for argument in arguments {
        let name = &argument.name;
        if let Some(&original_definition) = seen.get(name) {
            let redefined_definition = argument.location();
            diagnostics.push(
                ApolloDiagnostic::new(
                    db,
                    redefined_definition,
                    DiagnosticData::UniqueArgument {
                        name: name.to_string(),
                        original_definition,
                        redefined_definition,
                    },
                )
                .labels([
                    Label::new(
                        original_definition,
                        format!("previously provided `{name}` here"),
                    ),
                    Label::new(
                        redefined_definition,
                        format!("`{name}` provided again here"),
                    ),
                ])
                .help(format!("`{name}` argument must only be provided once.")),
            );
        } else {
            seen.insert(name, argument.location());
        }
    }

    diagnostics
}