use crate::{
    errors::Error,
    param_types::{EnumVariants, ParamType},
    Property,
};
use std::convert::TryFrom;
use std::str::FromStr;

impl TryFrom<&Property> for ParamType {
    type Error = Error;
    /// Turns a JSON property into ParamType
    fn try_from(prop: &Property) -> Result<Self, Self::Error> {
        match ParamType::from_str(&prop.type_field) {
            // Simple case (primitive types, no arrays, including string)
            Ok(param_type) => Ok(param_type),
            Err(_) => {
                if prop.type_field == "()" {
                    return Ok(ParamType::Unit);
                }
                if prop.type_field.starts_with('[') && prop.type_field.ends_with(']') {
                    return ParamType::parse_array_param(prop);
                }
                if prop.type_field.contains("str[") {
                    return ParamType::parse_string_param(prop);
                }
                if prop.type_field.starts_with('(') && prop.type_field.ends_with(')') {
                    // Try to parse tuple (T, T, ..., T)
                    return ParamType::parse_tuple_param(prop);
                }
                // Try to parse a free form enum or struct (e.g. `struct MySTruct`, `enum MyEnum`).
                ParamType::parse_custom_type_param(prop)
            }
        }
    }
}

impl ParamType {
    pub fn parse_tuple_param(prop: &Property) -> Result<Self, Error> {
        let mut params: Vec<Self> = Vec::new();

        for tuple_component in prop
            .components
            .as_ref()
            .expect("tuples should have components")
        {
            params.push(Self::try_from(tuple_component)?);
        }

        Ok(ParamType::Tuple(params))
    }

    pub fn parse_string_param(prop: &Property) -> Result<Self, Error> {
        // Split "str[n]" string into "str" and "[n]"
        let split: Vec<&str> = prop.type_field.split('[').collect();
        if split.len() != 2 || !split[0].eq("str") {
            return Err(Error::InvalidType(format!(
                "Expected parameter type `str[n]`, found `{}`",
                prop.type_field
            )));
        }
        // Grab size in between brackets, i.e the `n` in "[n]"
        let size: usize = split[1][..split[1].len() - 1].parse()?;
        Ok(ParamType::String(size))
    }

    pub fn parse_array_param(prop: &Property) -> Result<ParamType, Error> {
        // Split "[T; n]" string into "T" and "n"
        let split: Vec<&str> = prop.type_field.split("; ").collect();
        if split.len() != 2 {
            return Err(Error::InvalidType(format!(
                "Expected parameter type `[T; n]`, found `{}`",
                prop.type_field
            )));
        }
        let (type_field, size) = (split[0], split[1]);
        let type_field = type_field[1..].to_string();

        let param_type = match Self::from_str(&type_field) {
            Ok(param_type) => param_type,
            Err(_) => {
                let component = prop
                    .components
                    .as_ref()
                    .expect("array should have components")
                    .first()
                    .expect("components in array should have at least one component");

                if type_field.contains("str[") {
                    ParamType::parse_string_param(component)?
                } else {
                    ParamType::parse_custom_type_param(component)?
                }
            }
        };

        // Grab size the `n` in "[T; n]"
        let size: usize = size[..size.len() - 1].parse()?;
        Ok(ParamType::Array(Box::new(param_type), size))
    }

    pub fn parse_custom_type_param(prop: &Property) -> Result<ParamType, Error> {
        let mut params: Vec<ParamType> = vec![];
        match &prop.components {
            Some(c) => {
                for component in c {
                    params.push(Self::try_from(component)?)
                }
                if prop.is_struct_type() {
                    return Ok(ParamType::Struct(params));
                }
                if prop.is_enum_type() {
                    return Ok(ParamType::Enum(EnumVariants::new(params)?));
                }
                Err(Error::InvalidType(prop.type_field.clone()))
            }
            None => Err(Error::InvalidType(
                "cannot parse custom type with no components".into(),
            )),
        }
    }
}

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

    #[test]
    fn parse_string_and_array_param() -> Result<(), Error> {
        let array_prop = Property {
            name: "some_array".to_string(),
            type_field: "[bool; 4]".to_string(),
            components: None,
        };
        let expected = "Array(Box::new(ParamType::Bool),4)";
        let result = ParamType::parse_array_param(&array_prop)?.to_string();
        assert_eq!(result, expected);

        let string_prop = Property {
            name: "some_array".to_string(),
            type_field: "str[5]".to_string(),
            components: None,
        };
        let expected = "String(5)";
        let result = ParamType::parse_string_param(&string_prop)?.to_string();
        assert_eq!(result, expected);

        let expected = "Invalid type: Expected parameter type `str[n]`, found `[bool; 4]`";
        let result = ParamType::parse_string_param(&array_prop)
            .unwrap_err()
            .to_string();
        assert_eq!(result, expected);

        let expected = "Invalid type: Expected parameter type `[T; n]`, found `str[5]`";
        let result = ParamType::parse_array_param(&string_prop)
            .unwrap_err()
            .to_string();
        assert_eq!(result, expected);
        Ok(())
    }

    #[test]
    fn test_parse_custom_type_params() -> Result<(), Error> {
        let components = vec![
            Property {
                name: "vodka".to_string(),
                type_field: "u64".to_string(),
                components: None,
            },
            Property {
                name: "redbull".to_string(),
                type_field: "bool".to_string(),
                components: None,
            },
        ];

        // STRUCT
        let some_struct = Property {
            name: String::from("something_you_drink"),
            type_field: String::from("struct Cocktail"),
            components: Some(components.clone()),
        };
        let struct_result = ParamType::parse_custom_type_param(&some_struct)?;
        // Underlying value comparison
        let expected = ParamType::Struct(vec![ParamType::U64, ParamType::Bool]);
        assert_eq!(struct_result, expected);
        let expected_string = "Struct(vec![ParamType::U64,ParamType::Bool])";
        // String format comparison
        assert_eq!(struct_result.to_string(), expected_string);

        // ENUM
        let some_enum = Property {
            name: String::from("something_you_drink"),
            type_field: String::from("enum Cocktail"),
            components: Some(components),
        };
        let enum_result = ParamType::parse_custom_type_param(&some_enum)?;
        // Underlying value comparison
        let expected = ParamType::Enum(EnumVariants::new(vec![ParamType::U64, ParamType::Bool])?);
        assert_eq!(enum_result, expected);
        let expected_string =
            "Enum(EnumVariants::new(vec![ParamType::U64,ParamType::Bool]).unwrap())";
        // String format comparison
        assert_eq!(enum_result.to_string(), expected_string);
        Ok(())
    }
}