use std::collections::HashSet;

use parser::types::{Directive, Field};
use parser::Positioned;
use value::{Name, Value};

use crate::{Visitor, VisitorContext};

#[derive(Default)]
pub struct UniqueArgumentNames<'a> {
    names: HashSet<&'a str>,
}

impl<'a> Visitor<'a> for UniqueArgumentNames<'a> {
    fn enter_directive(
        &mut self,
        _ctx: &mut VisitorContext<'a>,
        _directive: &'a Positioned<Directive>,
    ) {
        self.names.clear();
    }

    fn enter_argument(
        &mut self,
        ctx: &mut VisitorContext<'a>,
        name: &'a Positioned<Name>,
        _value: &'a Positioned<Value>,
    ) {
        if !self.names.insert(name.node.as_str()) {
            ctx.report_error(
                vec![name.pos],
                format!("There can only be one argument named \"{}\"", name),
            )
        }
    }

    fn enter_field(&mut self, _ctx: &mut VisitorContext<'a>, _field: &'a Positioned<Field>) {
        self.names.clear();
    }
}

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

    pub fn factory<'a>() -> UniqueArgumentNames<'a> {
        UniqueArgumentNames::default()
    }

    #[test]
    fn no_arguments_on_field() {
        expect_passes_rule!(
            factory,
            r#"
          {
            field
          }
        "#,
        );
    }

    #[test]
    fn no_arguments_on_directive() {
        expect_passes_rule!(
            factory,
            r#"
          {
            dog @directive
          }
        "#,
        );
    }

    #[test]
    fn argument_on_field() {
        expect_passes_rule!(
            factory,
            r#"
          {
            field(arg: "value")
          }
        "#,
        );
    }

    #[test]
    fn argument_on_directive() {
        expect_passes_rule!(
            factory,
            r#"
          {
            dog @directive(arg: "value")
          }
        "#,
        );
    }

    #[test]
    fn same_argument_on_two_fields() {
        expect_passes_rule!(
            factory,
            r#"
          {
            one: field(arg: "value")
            two: field(arg: "value")
          }
        "#,
        );
    }

    #[test]
    fn same_argument_on_field_and_directive() {
        expect_passes_rule!(
            factory,
            r#"
          {
            field(arg: "value") @directive(arg: "value")
          }
        "#,
        );
    }

    #[test]
    fn same_argument_on_two_directives() {
        expect_passes_rule!(
            factory,
            r#"
          {
            field @directive1(arg: "value") @directive2(arg: "value")
          }
        "#,
        );
    }

    #[test]
    fn multiple_field_arguments() {
        expect_passes_rule!(
            factory,
            r#"
          {
            field(arg1: "value", arg2: "value", arg3: "value")
          }
        "#,
        );
    }

    #[test]
    fn multiple_directive_arguments() {
        expect_passes_rule!(
            factory,
            r#"
          {
            field @directive(arg1: "value", arg2: "value", arg3: "value")
          }
        "#,
        );
    }

    #[test]
    fn duplicate_field_arguments() {
        expect_fails_rule!(
            factory,
            r#"
          {
            field(arg1: "value", arg1: "value")
          }
        "#,
        );
    }

    #[test]
    fn many_duplicate_field_arguments() {
        expect_fails_rule!(
            factory,
            r#"
          {
            field(arg1: "value", arg1: "value", arg1: "value")
          }
        "#,
        );
    }

    #[test]
    fn duplicate_directive_arguments() {
        expect_fails_rule!(
            factory,
            r#"
          {
            field @directive(arg1: "value", arg1: "value")
          }
        "#,
        );
    }

    #[test]
    fn many_duplicate_directive_arguments() {
        expect_fails_rule!(
            factory,
            r#"
          {
            field @directive(arg1: "value", arg1: "value", arg1: "value")
          }
        "#,
        );
    }
}
