use chrono::{DateTime, Utc};
use derive_builder::Builder;
use interim_pgtypes::pg_attribute::PgAttribute;
use serde::{Deserialize, Serialize};
use sqlx::{Decode, Postgres, Row as _, TypeInfo as _, ValueRef as _, postgres::PgRow, query_as};
use thiserror::Error;
use uuid::Uuid;

use crate::client::AppDbClient;

pub const RFC_3339_S: &str = "%Y-%m-%dT%H:%M:%S";

#[derive(Clone, Debug, Deserialize, Serialize)]
pub struct Field {
    pub id: Uuid,
    pub name: String,
    pub label: Option<String>,
    pub field_type: sqlx::types::Json<FieldType>,
    pub width_px: i32,
}

impl Field {
    pub fn insertable_builder() -> InsertableFieldBuilder {
        InsertableFieldBuilder::default()
    }

    pub fn default_from_attr(attr: &PgAttribute) -> Self {
        Self {
            id: Uuid::now_v7(),
            name: attr.attname.clone(),
            label: None,
            field_type: sqlx::types::Json(FieldType::default_from_attr(attr)),
            width_px: 200,
        }
    }

    pub fn webc_tag(&self) -> &str {
        match self.field_type.0 {
            FieldType::InterimUser {} => "cell-interim-user",
            FieldType::Text {} => "cell-text",
            FieldType::Timestamp { .. } => "cell-timestamp",
            FieldType::Uuid {} => "cell-uuid",
            FieldType::Unknown => "cell-unknown",
        }
    }

    pub fn webc_custom_attrs(&self) -> Vec<(String, String)> {
        vec![]
    }

    pub fn get_value_encodable(&self, row: &PgRow) -> Result<Encodable, ParseError> {
        let value_ref = row
            .try_get_raw(self.name.as_str())
            .or(Err(ParseError::FieldNotFound))?;
        let type_info = value_ref.type_info();
        let ty = type_info.name();
        Ok(match ty {
            "TEXT" | "VARCHAR" => {
                Encodable::Text(<Option<String> as Decode<Postgres>>::decode(value_ref).unwrap())
            }
            "UUID" => {
                Encodable::Uuid(<Option<Uuid> as Decode<Postgres>>::decode(value_ref).unwrap())
            }
            _ => return Err(ParseError::UnknownType),
        })
    }

    pub fn belonging_to_lens(lens_id: Uuid) -> BelongingToLensQuery {
        BelongingToLensQuery { lens_id }
    }
}

#[derive(Clone, Debug)]
pub struct BelongingToLensQuery {
    lens_id: Uuid,
}

impl BelongingToLensQuery {
    pub async fn fetch_all(self, app_db: &mut AppDbClient) -> Result<Vec<Field>, sqlx::Error> {
        query_as!(
            Field,
            r#"
select
    id,
    name,
    label,
    field_type as "field_type: sqlx::types::Json<FieldType>",
    width_px
from fields
where lens_id = $1
"#,
            self.lens_id
        )
        .fetch_all(&mut *app_db.conn)
        .await
    }
}

#[derive(Clone, Debug, Deserialize, Serialize)]
#[serde(tag = "t", content = "c")]
pub enum FieldType {
    InterimUser {},
    Text {},
    Timestamp {
        format: String,
    },
    Uuid {},
    /// A special variant for when the field type is not specified and cannot be
    /// inferred. This isn't represented as an error, because we still want to
    /// be able to define display behavior via the .render() method.
    Unknown,
}

impl FieldType {
    pub fn default_from_attr(attr: &PgAttribute) -> Self {
        match attr.regtype.as_str() {
            "text" => Self::Text {},
            "timestamp" => Self::Timestamp {
                format: RFC_3339_S.to_owned(),
            },
            "uuid" => Self::Uuid {},
            _ => Self::Unknown,
        }
    }

    /// Returns a SQL fragment for the default data type for creating or
    /// altering a backing column, such as "integer", or "timestamptz". Returns
    /// None if the field type is Unknown.
    pub fn attr_data_type_fragment(&self) -> Option<&'static str> {
        match self {
            Self::InterimUser {} | Self::Text {} => Some("text"),
            Self::Timestamp { .. } => Some("timestamptz"),
            Self::Uuid { .. } => Some("uuid"),
            Self::Unknown => None,
        }
    }
}

#[derive(Clone, Debug, Error)]
#[error("field type is unknown")]
pub struct FieldTypeUnknownError {}

// -------- Insertable --------

#[derive(Builder, Clone, Debug)]
pub struct InsertableField {
    lens_id: Uuid,
    name: String,
    #[builder(default)]
    label: Option<String>,
    field_type: FieldType,
    #[builder(default = 200)]
    width_px: i32,
}

impl InsertableField {
    pub async fn insert(self, app_db: &mut AppDbClient) -> Result<Field, sqlx::Error> {
        query_as!(
            Field,
            r#"
insert into fields
(id, lens_id, name, label, field_type, width_px)
values ($1, $2, $3, $4, $5, $6)
returning
    id,
    name,
    label,
    field_type as "field_type: sqlx::types::Json<FieldType>",
    width_px
"#,
            Uuid::now_v7(),
            self.lens_id,
            self.name,
            self.label,
            sqlx::types::Json::<_>(self.field_type) as sqlx::types::Json<FieldType>,
            self.width_px,
        )
        .fetch_one(&mut *app_db.conn)
        .await
    }
}

impl InsertableFieldBuilder {
    pub fn default_from_attr(attr: &PgAttribute) -> Self {
        Self {
            name: Some(attr.attname.clone()),
            field_type: Some(FieldType::default_from_attr(attr)),
            ..Self::default()
        }
    }
}

// -------- Errors --------

/// Error when parsing a sqlx value to JSON
#[derive(Debug, Error)]
pub enum ParseError {
    #[error("incompatible json type")]
    BadJsonType,
    #[error("field not found in row")]
    FieldNotFound,
    #[error("unknown postgres type")]
    UnknownType,
}

// -------- Encodable --------
// TODO this should probably be moved to another crate

#[derive(Clone, Debug, Deserialize, PartialEq, Serialize)]
#[serde(tag = "t", content = "c")]
pub enum Encodable {
    Text(Option<String>),
    Timestamp(Option<DateTime<Utc>>),
    Uuid(Option<Uuid>),
}

impl Encodable {
    pub fn bind_onto<'a>(
        self,
        query: sqlx::query::Query<'a, Postgres, <sqlx::Postgres as sqlx::Database>::Arguments<'a>>,
    ) -> sqlx::query::Query<'a, Postgres, <sqlx::Postgres as sqlx::Database>::Arguments<'a>> {
        match self {
            Self::Text(value) => query.bind(value),
            Self::Timestamp(value) => query.bind(value),
            Self::Uuid(value) => query.bind(value),
        }
    }

    /// Transform the contained value into a serde_json::Value.
    pub fn inner_as_value(&self) -> serde_json::Value {
        let serialized = serde_json::to_value(self).unwrap();
        #[derive(Deserialize)]
        struct Tagged {
            c: serde_json::Value,
        }
        let deserialized: Tagged = serde_json::from_value(serialized).unwrap();
        deserialized.c
    }

    pub fn is_none(&self) -> bool {
        match self {
            Self::Text(None) | Self::Timestamp(None) | Self::Uuid(None) => true,
            Self::Text(_) | Self::Timestamp(_) | Self::Uuid(_) => false,
        }
    }
}