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();
    }

    // There are borrow issues here that seems too difficult to solve.
    // The errors 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.

    for recipe in recipes.values() {
      for line in &recipe.lines {
        for fragment in line {
          if let Fragment::Expression{ref expression, ..} = *fragment {
            for function in expression.functions() {
              if let Err(error) = ::functions::resolve_function(function) {
                return Err(CompilationError {
                  text:   text,
                  index:  error.index,
                  line:   error.line,
                  column: error.column,
                  width:  error.width,
                  kind:   UnknownFunction {
                    function: &text[error.index..error.index + error.width.unwrap()],
                  }
                });
              }
            }
            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 {
                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::*;

  compilation_error_test! {
    name:   circular_recipe_dependency,
    input:  "a: b\nb: a",
    index:  8,
    line:   1,
    column: 3,
    width:  Some(1),
    kind:   CircularRecipeDependency{recipe: "b", circle: vec!["a", "b", "a"]},
  }

  compilation_error_test! {
    name:   self_recipe_dependency,
    input:  "a: a",
    index:  3,
    line:   0,
    column: 3,
    width:  Some(1),
    kind:   CircularRecipeDependency{recipe: "a", circle: vec!["a", "a"]},
  }

  compilation_error_test! {
    name:   unknown_dependency,
    input:  "a: b",
    index:  3,
    line:   0,
    column: 3,
    width:  Some(1),
    kind:   UnknownDependency{recipe: "a", unknown: "b"},
  }

  compilation_error_test! {
    name:   unknown_interpolation_variable,
    input:  "x:\n {{   hello}}",
    index:  9,
    line:   1,
    column: 6,
    width:  Some(5),
    kind:   UndefinedVariable{variable: "hello"},
  }

  compilation_error_test! {
    name:   unknown_second_interpolation_variable,
    input:  "wtf=\"x\"\nx:\n echo\n foo {{wtf}} {{ lol }}",
    index:  33,
    line:   3,
    column: 16,
    width:  Some(3),
    kind:   UndefinedVariable{variable: "lol"},
  }

  compilation_error_test! {
    name:   unknown_function_in_interpolation,
    input:  "a:\n echo {{bar()}}",
    index:  11,
    line:   1,
    column: 8,
    width:  Some(3),
    kind:   UnknownFunction{function: "bar"},
  }
}