use common::*;

use CompilationErrorKind::*;

pub struct RecipeResolver<'a: 'b, 'b> {
  stack:    Vec<&'a str>,
  seen:     Set<&'a str>,
  resolved: Set<&'a str>,
  recipes:  &'b Map<&'a str, Recipe<'a>>,
}

impl<'a, 'b> RecipeResolver<'a, 'b> {
  pub fn resolve_recipes(
    recipes:     &Map<&'a str, Recipe<'a>>,
    assignments: &Map<&'a str, Expression<'a>>,
    text:        &'a str,
  ) -> CompilationResult<'a, ()> {
    let mut resolver = RecipeResolver {
      seen:              empty(),
      stack:             empty(),
      resolved:          empty(),
      recipes:           recipes,
    };

    for recipe in recipes.values() {
      resolver.resolve_recipe(recipe)?;
      resolver.seen = empty();
    }

    for recipe in recipes.values() {
      for line in &recipe.lines {
        for fragment in line {
          if let Fragment::Expression{ref expression, ..} = *fragment {
            for variable in expression.variables() {
              let name = variable.lexeme;
              let undefined = !assignments.contains_key(name)
                && !recipe.parameters.iter().any(|p| p.name == name);
              if undefined {
                // There's a borrow issue here that seems too difficult to solve.
                // The error derived from the variable token has too short a lifetime,
                // so we create a new error from its contents, which do live long
                // enough.
                //
                // I suspect the solution here is to give recipes, pieces, and expressions
                // two lifetime parameters instead of one, with one being the lifetime
                // of the struct, and the second being the lifetime of the tokens
                // that it contains
                let error = variable.error(UndefinedVariable{variable: name});
                return Err(CompilationError {
                  text:   text,
                  index:  error.index,
                  line:   error.line,
                  column: error.column,
                  width:  error.width,
                  kind:   UndefinedVariable {
                    variable: &text[error.index..error.index + error.width.unwrap()],
                  }
                });
              }
            }
          }
        }
      }
    }

    Ok(())
  }

  fn resolve_recipe(&mut self, recipe: &Recipe<'a>) -> CompilationResult<'a, ()> {
    if self.resolved.contains(recipe.name) {
      return Ok(())
    }
    self.stack.push(recipe.name);
    self.seen.insert(recipe.name);
    for dependency_token in &recipe.dependency_tokens {
      match self.recipes.get(dependency_token.lexeme) {
        Some(dependency) => if !self.resolved.contains(dependency.name) {
          if self.seen.contains(dependency.name) {
            let first = self.stack[0];
            self.stack.push(first);
            return Err(dependency_token.error(CircularRecipeDependency {
              recipe: recipe.name,
              circle: self.stack.iter()
                .skip_while(|name| **name != dependency.name)
                .cloned().collect()
            }));
          }
          self.resolve_recipe(dependency)?;
        },
        None => return Err(dependency_token.error(UnknownDependency {
          recipe:  recipe.name,
          unknown: dependency_token.lexeme
        })),
      }
    }
    self.resolved.insert(recipe.name);
    self.stack.pop();
    Ok(())
  }
}

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

  #[test]
  fn circular_recipe_dependency() {
    let text   = "a: b\nb: a";
    let recipe = "b";
    let circle = vec!["a", "b", "a"];
    parse_error(text, CompilationError {
      text:   text,
      index:  8,
      line:   1,
      column: 3,
      width:  Some(1),
      kind:   CircularRecipeDependency{recipe, circle}
    });
  }

  #[test]
  fn self_recipe_dependency() {
    let text = "a: a";
    parse_error(text, CompilationError {
      text:   text,
      index:  3,
      line:   0,
      column: 3,
      width:  Some(1),
      kind:   CircularRecipeDependency{recipe: "a", circle: vec!["a", "a"]}
    });
  }

  #[test]
  fn unknown_dependency() {
    let text = "a: b";
    parse_error(text, CompilationError {
      text:   text,
      index:  3,
      line:   0,
      column: 3,
      width:  Some(1),
      kind:   UnknownDependency{recipe: "a", unknown: "b"}
    });
  }

  #[test]
  fn unknown_interpolation_variable() {
    let text = "x:\n {{   hello}}";
    parse_error(text, CompilationError {
      text:   text,
      index:  9,
      line:   1,
      column: 6,
      width:  Some(5),
      kind:   UndefinedVariable{variable: "hello"},
    });
  }

  #[test]
  fn unknown_second_interpolation_variable() {
    let text = "wtf=\"x\"\nx:\n echo\n foo {{wtf}} {{ lol }}";
    parse_error(text, CompilationError {
      text:   text,
      index:  33,
      line:   3,
      column: 16,
      width:  Some(3),
      kind:   UndefinedVariable{variable: "lol"},
    });
  }
}