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use crate::{
    types::SqlType,
    ColumnName,
    FromDao,
    TableName,
};
use uuid::Uuid;

#[derive(Debug, PartialEq, Clone)]
pub struct ColumnDef {
    pub table: TableName,
    pub name: ColumnName,
    pub comment: Option<String>,
    pub specification: ColumnSpecification,
    pub stat: Option<ColumnStat>,
}

impl ColumnDef {
    /// check all the column constraint if any has AutoIncrement
    pub fn is_autoincrement(&self) -> bool { self.autoincrement_sequence_name().is_some() }

    /// get the sequnce name of this autoincrement column
    pub fn autoincrement_sequence_name(&self) -> Option<&String> {
        self.specification.constraints.iter().find_map(|c| {
            match &c {
                ColumnConstraint::AutoIncrement(sequence_name) => sequence_name.as_ref(),
                _ => None,
            }
        })
    }

    /// check if any of the column constraint default is generated from uuid
    pub fn default_is_generated_uuid(&self) -> bool {
        self.specification
            .constraints
            .iter()
            .any(|c| matches!(*c, ColumnConstraint::DefaultValue(Literal::UuidGenerateV4)))
    }

    pub fn is_not_null(&self) -> bool {
        self.specification
            .constraints
            .iter()
            .any(|c| matches!(*c, ColumnConstraint::NotNull))
    }

    pub fn get_sql_type(&self) -> SqlType { self.specification.sql_type.clone() }

    pub fn cast_as(&self) -> Option<SqlType> { self.get_sql_type().cast_as() }

    pub fn has_generated_default(&self) -> bool {
        self.specification.constraints.iter().any(|c| {
            match *c {
                ColumnConstraint::DefaultValue(ref literal) => {
                    match *literal {
                        Literal::Bool(_) => true,
                        Literal::Null => false,
                        Literal::Integer(_) => true,
                        Literal::Double(_) => true,
                        Literal::UuidGenerateV4 => true,
                        Literal::Uuid(_) => true,
                        Literal::String(_) => false,
                        Literal::Blob(_) => false,
                        Literal::CurrentTime => true,
                        Literal::CurrentDate => true,
                        Literal::CurrentTimestamp => true,
                        Literal::ArrayInt(_) => false,
                        Literal::ArrayFloat(_) => false,
                        Literal::ArrayString(_) => false,
                    }
                }
                _ => false,
            }
        })
    }
}

#[derive(Debug, PartialEq, Clone)]
pub struct ColumnSpecification {
    pub sql_type: SqlType,
    pub capacity: Option<Capacity>,
    pub constraints: Vec<ColumnConstraint>,
}

impl ColumnSpecification {
    pub fn get_limit(&self) -> Option<i32> {
        match self.capacity {
            Some(ref capacity) => capacity.get_limit(),
            None => None,
        }
    }
}

#[derive(Debug, PartialEq, Clone)]
pub enum Capacity {
    Limit(i32),
    Range(i32, i32),
}

impl Capacity {
    fn get_limit(&self) -> Option<i32> {
        match *self {
            Capacity::Limit(limit) => Some(limit),
            Capacity::Range(_whole, _decimal) => None,
        }
    }
}

#[derive(Debug, PartialEq, Clone)]
pub enum ColumnConstraint {
    NotNull,
    DefaultValue(Literal),
    /// the string contains the sequence name of this serial column
    AutoIncrement(Option<String>),
}

#[derive(Debug, PartialEq, Clone)]
pub enum Literal {
    Bool(bool),
    Null,
    Integer(i64),
    Double(f64),
    UuidGenerateV4, // pg: uuid_generate_v4();
    Uuid(Uuid),
    String(String),
    Blob(Vec<u8>),
    CurrentTime,      // pg: now()
    CurrentDate,      //pg: today()
    CurrentTimestamp, // pg: now()
    ArrayInt(Vec<i64>),
    ArrayFloat(Vec<f64>),
    ArrayString(Vec<String>),
}

/// column stat, derive from pg_stats
#[derive(Debug, PartialEq, FromDao, Clone)]
pub struct ColumnStat {
    pub avg_width: i32, /* average width of the column, (the number of characters) */
    //most_common_values: Value,//top 5 most common values
    pub n_distinct: f32, // the number of distinct values of these column
}

impl From<i64> for Literal {
    fn from(i: i64) -> Self { Literal::Integer(i) }
}

impl From<String> for Literal {
    fn from(s: String) -> Self { Literal::String(s) }
}

impl<'a> From<&'a str> for Literal {
    fn from(s: &'a str) -> Self { Literal::String(String::from(s)) }
}