use base64::decode;

use crate::schema::Facet;
use crate::schema::IndexRecordOption;
use crate::schema::TextFieldIndexing;
use crate::schema::Value;
use crate::schema::{IntOptions, TextOptions};
use crate::tokenizer::PreTokenizedString;
use chrono::{FixedOffset, Utc};
use serde_json::Value as JsonValue;

/// Possible error that may occur while parsing a field value
/// At this point the JSON is known to be valid.
#[derive(Debug, PartialEq)]
pub enum ValueParsingError {
    /// Encountered a numerical value that overflows or underflow its integer type.
    OverflowError(String),
    /// The json node is not of the correct type.
    /// (e.g. 3 for a `Str` type or `"abc"` for a u64 type)
    /// Tantivy will try to autocast values.
    TypeError(String),
    /// The json node is a string but contains json that is
    /// not valid base64.
    InvalidBase64(String),
}

/// Type of the value that a field can take.
///
/// Contrary to FieldType, this does
/// not include the way the field must be indexed.
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum Type {
    /// `&str`
    Str,
    /// `u64`
    U64,
    /// `i64`
    I64,
    /// `f64`
    F64,
    /// `date(i64) timestamp`
    Date,
    /// `tantivy::schema::Facet`. Passed as a string in JSON.
    HierarchicalFacet,
    /// `Vec<u8>`
    Bytes,
}

/// A `FieldType` describes the type (text, u64) of a field as well as
/// how it should be handled by tantivy.
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum FieldType {
    /// String field type configuration
    Str(TextOptions),
    /// Unsigned 64-bits integers field type configuration
    U64(IntOptions),
    /// Signed 64-bits integers 64 field type configuration
    I64(IntOptions),
    /// 64-bits float 64 field type configuration
    F64(IntOptions),
    /// Signed 64-bits Date 64 field type configuration,
    Date(IntOptions),
    /// Hierachical Facet
    HierarchicalFacet,
    /// Bytes (one per document)
    Bytes,
}

impl FieldType {
    /// Returns the value type associated for this field.
    pub fn value_type(&self) -> Type {
        match *self {
            FieldType::Str(_) => Type::Str,
            FieldType::U64(_) => Type::U64,
            FieldType::I64(_) => Type::I64,
            FieldType::F64(_) => Type::F64,
            FieldType::Date(_) => Type::Date,
            FieldType::HierarchicalFacet => Type::HierarchicalFacet,
            FieldType::Bytes => Type::Bytes,
        }
    }

    /// returns true iff the field is indexed.
    pub fn is_indexed(&self) -> bool {
        match *self {
            FieldType::Str(ref text_options) => text_options.get_indexing_options().is_some(),
            FieldType::U64(ref int_options)
            | FieldType::I64(ref int_options)
            | FieldType::F64(ref int_options) => int_options.is_indexed(),
            FieldType::Date(ref date_options) => date_options.is_indexed(),
            FieldType::HierarchicalFacet => true,
            FieldType::Bytes => false,
        }
    }

    /// Given a field configuration, return the maximal possible
    /// `IndexRecordOption` available.
    ///
    /// If the field is not indexed, then returns `None`.
    pub fn get_index_record_option(&self) -> Option<IndexRecordOption> {
        match *self {
            FieldType::Str(ref text_options) => text_options
                .get_indexing_options()
                .map(TextFieldIndexing::index_option),
            FieldType::U64(ref int_options)
            | FieldType::I64(ref int_options)
            | FieldType::F64(ref int_options)
            | FieldType::Date(ref int_options) => {
                if int_options.is_indexed() {
                    Some(IndexRecordOption::Basic)
                } else {
                    None
                }
            }
            FieldType::HierarchicalFacet => Some(IndexRecordOption::Basic),
            FieldType::Bytes => None,
        }
    }

    /// Parses a field value from json, given the target FieldType.
    ///
    /// Tantivy will not try to cast values.
    /// For instance, If the json value is the integer `3` and the
    /// target field is a `Str`, this method will return an Error.
    pub fn value_from_json(&self, json: &JsonValue) -> Result<Value, ValueParsingError> {
        match *json {
            JsonValue::String(ref field_text) => match *self {
                FieldType::Date(_) => {
                    let dt_with_fixed_tz: chrono::DateTime<FixedOffset> =
                        chrono::DateTime::parse_from_rfc3339(field_text).map_err(|err|
                            ValueParsingError::TypeError(format!(
                                "Failed to parse date from JSON. Expected rfc3339 format, got {}. {:?}",
                                field_text, err
                            ))
                        )?;
                    Ok(Value::Date(dt_with_fixed_tz.with_timezone(&Utc)))
                }
                FieldType::Str(_) => Ok(Value::Str(field_text.clone())),
                FieldType::U64(_) | FieldType::I64(_) | FieldType::F64(_) => Err(
                    ValueParsingError::TypeError(format!("Expected an integer, got {:?}", json)),
                ),
                FieldType::HierarchicalFacet => Ok(Value::Facet(Facet::from(field_text))),
                FieldType::Bytes => decode(field_text).map(Value::Bytes).map_err(|_| {
                    ValueParsingError::InvalidBase64(format!(
                        "Expected base64 string, got {:?}",
                        field_text
                    ))
                }),
            },
            JsonValue::Number(ref field_val_num) => match *self {
                FieldType::I64(_) | FieldType::Date(_) => {
                    if let Some(field_val_i64) = field_val_num.as_i64() {
                        Ok(Value::I64(field_val_i64))
                    } else {
                        let msg = format!("Expected an i64 int, got {:?}", json);
                        Err(ValueParsingError::OverflowError(msg))
                    }
                }
                FieldType::U64(_) => {
                    if let Some(field_val_u64) = field_val_num.as_u64() {
                        Ok(Value::U64(field_val_u64))
                    } else {
                        let msg = format!("Expected a u64 int, got {:?}", json);
                        Err(ValueParsingError::OverflowError(msg))
                    }
                }
                FieldType::F64(_) => {
                    if let Some(field_val_f64) = field_val_num.as_f64() {
                        Ok(Value::F64(field_val_f64))
                    } else {
                        let msg = format!("Expected a f64 int, got {:?}", json);
                        Err(ValueParsingError::OverflowError(msg))
                    }
                }
                FieldType::Str(_) | FieldType::HierarchicalFacet | FieldType::Bytes => {
                    let msg = format!("Expected a string, got {:?}", json);
                    Err(ValueParsingError::TypeError(msg))
                }
            },
            JsonValue::Object(_) => match *self {
                FieldType::Str(_) => {
                    if let Ok(tok_str_val) =
                        serde_json::from_value::<PreTokenizedString>(json.clone())
                    {
                        Ok(Value::PreTokStr(tok_str_val))
                    } else {
                        let msg = format!(
                            "Json value {:?} cannot be translated to PreTokenizedString.",
                            json
                        );
                        Err(ValueParsingError::TypeError(msg))
                    }
                }
                _ => {
                    let msg = format!(
                        "Json value not supported error {:?}. Expected {:?}",
                        json, self
                    );
                    Err(ValueParsingError::TypeError(msg))
                }
            },
            _ => {
                let msg = format!(
                    "Json value not supported error {:?}. Expected {:?}",
                    json, self
                );
                Err(ValueParsingError::TypeError(msg))
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use super::FieldType;
    use crate::schema::field_type::ValueParsingError;
    use crate::schema::TextOptions;
    use crate::schema::Value;
    use crate::schema::{Schema, INDEXED};
    use crate::tokenizer::{PreTokenizedString, Token};
    use crate::{DateTime, Document};
    use chrono::{NaiveDate, NaiveDateTime, NaiveTime, Utc};

    #[test]
    fn test_deserialize_json_date() {
        let mut schema_builder = Schema::builder();
        let date_field = schema_builder.add_date_field("date", INDEXED);
        let schema = schema_builder.build();
        let doc_json = r#"{"date": "2019-10-12T07:20:50.52+02:00"}"#;
        let doc = schema.parse_document(doc_json).unwrap();
        let date = doc.get_first(date_field).unwrap();
        assert_eq!(format!("{:?}", date), "Date(2019-10-12T05:20:50.520Z)");
    }

    #[test]
    fn test_serialize_json_date() {
        let mut doc = Document::new();
        let mut schema_builder = Schema::builder();
        let date_field = schema_builder.add_date_field("date", INDEXED);
        let schema = schema_builder.build();
        let naive_date = NaiveDate::from_ymd(1982, 9, 17);
        let naive_time = NaiveTime::from_hms(13, 20, 00);
        let date_time = DateTime::from_utc(NaiveDateTime::new(naive_date, naive_time), Utc);
        doc.add_date(date_field, &date_time);
        let doc_json = schema.to_json(&doc);
        assert_eq!(doc_json, r#"{"date":["1982-09-17T13:20:00+00:00"]}"#);
    }

    #[test]
    fn test_bytes_value_from_json() {
        let result = FieldType::Bytes
            .value_from_json(&json!("dGhpcyBpcyBhIHRlc3Q="))
            .unwrap();
        assert_eq!(result, Value::Bytes("this is a test".as_bytes().to_vec()));

        let result = FieldType::Bytes.value_from_json(&json!(521));
        match result {
            Err(ValueParsingError::TypeError(_)) => {}
            _ => panic!("Expected parse failure for wrong type"),
        }

        let result = FieldType::Bytes.value_from_json(&json!("-"));
        match result {
            Err(ValueParsingError::InvalidBase64(_)) => {}
            _ => panic!("Expected parse failure for invalid base64"),
        }
    }

    #[test]
    fn test_pre_tok_str_value_from_json() {
        let pre_tokenized_string_json = r#"{
  "text": "The Old Man",
  "tokens": [
    {
      "offset_from": 0,
      "offset_to": 3,
      "position": 0,
      "text": "The",
      "position_length": 1
    },
    {
      "offset_from": 4,
      "offset_to": 7,
      "position": 1,
      "text": "Old",
      "position_length": 1
    },
    {
      "offset_from": 8,
      "offset_to": 11,
      "position": 2,
      "text": "Man",
      "position_length": 1
    }
  ]
}"#;

        let expected_value = Value::PreTokStr(PreTokenizedString {
            text: String::from("The Old Man"),
            tokens: vec![
                Token {
                    offset_from: 0,
                    offset_to: 3,
                    position: 0,
                    text: String::from("The"),
                    position_length: 1,
                },
                Token {
                    offset_from: 4,
                    offset_to: 7,
                    position: 1,
                    text: String::from("Old"),
                    position_length: 1,
                },
                Token {
                    offset_from: 8,
                    offset_to: 11,
                    position: 2,
                    text: String::from("Man"),
                    position_length: 1,
                },
            ],
        });

        let deserialized_value = FieldType::Str(TextOptions::default())
            .value_from_json(&serde_json::from_str(pre_tokenized_string_json).unwrap())
            .unwrap();

        assert_eq!(deserialized_value, expected_value);

        let serialized_value_json = serde_json::to_string_pretty(&expected_value).unwrap();

        assert_eq!(serialized_value_json, pre_tokenized_string_json);
    }
}