// Copyright 2016 Mozilla
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
// this file except in compliance with the License. You may obtain a copy of the
// License at http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software distributed
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.

extern crate mentat_query;

use mentat_core::{
    EdnParseError,
    ValueType,
    ValueTypeSet,
};

use self::mentat_query::{
    PlainSymbol,
};

#[derive(Clone, Debug, Eq, PartialEq)]
pub enum BindingError {
    NoBoundVariable,
    UnexpectedBinding,
    RepeatedBoundVariable, // TODO: include repeated variable(s).

    /// Expected `[[?x ?y]]` but got some other type of binding.  Mentat is deliberately more strict
    /// than Datomic: we won't try to make sense of non-obvious (and potentially erroneous) bindings.
    ExpectedBindRel,

    /// Expected `[[?x ?y]]` or `[?x ...]` but got some other type of binding.  Mentat is
    /// deliberately more strict than Datomic: we won't try to make sense of non-obvious (and
    /// potentially erroneous) bindings.
    ExpectedBindRelOrBindColl,

    /// Expected `[?x1 … ?xN]` or `[[?x1 … ?xN]]` but got some other number of bindings.  Mentat is
    /// deliberately more strict than Datomic: we prefer placeholders to omission.
    InvalidNumberOfBindings { number: usize, expected: usize },
}

error_chain! {
    types {
        Error, ErrorKind, ResultExt, Result;
    }

    foreign_links {
        EdnParseError(EdnParseError);
    }

    errors {
        UnsupportedArgument {
            description("unexpected FnArg")
            display("unexpected FnArg")
        }

        InputTypeDisagreement(var: PlainSymbol, declared: ValueType, provided: ValueType) {
            description("input type disagreement")
            display("value of type {} provided for var {}, expected {}", provided, var, declared)
        }

        UnrecognizedIdent(ident: String) {
            description("no entid found for ident")
            display("no entid found for ident: {}", ident)
        }

        UnknownFunction(name: PlainSymbol) {
            description("no such function")
            display("no function named {}", name)
        }

        InvalidNumberOfArguments(function: PlainSymbol, number: usize, expected: usize) {
            description("invalid number of arguments")
            display("invalid number of arguments to {}: expected {}, got {}.", function, expected, number)
        }

        UnboundVariable(name: PlainSymbol) {
            description("unbound variable in order clause or function call")
            display("unbound variable: {}", name)
        }

        InvalidBinding(function: PlainSymbol, binding_error: BindingError) {
            description("invalid binding")
            display("invalid binding for {}: {:?}.", function, binding_error)
        }

        GroundBindingsMismatch {
            description("mismatched bindings in ground")
            display("mismatched bindings in ground")
        }

        InvalidGroundConstant {
            // TODO: flesh this out.
            description("invalid expression in ground constant")
            display("invalid expression in ground constant")
        }

        InvalidArgument(function: PlainSymbol, expected: &'static str, position: usize) {
            description("invalid argument")
            display("invalid argument to {}: expected {} in position {}.", function, expected, position)
        }

        InvalidArgumentType(function: PlainSymbol, expected_types: ValueTypeSet, position: usize) {
            description("invalid argument")
            display("invalid argument to {}: expected one of {:?} in position {}.", function, expected_types, position)
        }

        InvalidLimit(val: String, kind: ValueType) {
            description("invalid limit")
            display("invalid limit {} of type {}: expected natural number.", val, kind)
        }

        NonMatchingVariablesInOrClause {
            // TODO: flesh out.
            description("non-matching variables in 'or' clause")
            display("non-matching variables in 'or' clause")
        }

        NonMatchingVariablesInNotClause {
            // TODO: flesh out.
            description("non-matching variables in 'not' clause")
            display("non-matching variables in 'not' clause")
        }

        DuplicateVariableError(name: PlainSymbol, clause: &'static str)  {
            description("duplicate variables")
            display("{} var {} is duplicated", clause, name)
        }

        UnknownLimitVar(name: PlainSymbol) {
            description(":limit var not present in :in")
            display(":limit var {} not present in :in", name)
        }
    }
}