//! Metadata about circuits.

use super::metadata::Column as ColumnMetadata;
use crate::plonk;
use halo2_middleware::circuit::Any;
pub use halo2_middleware::circuit::ColumnMid as Column;
use std::{
    collections::HashMap,
    fmt::{self, Debug},
};

/// A helper structure that allows to print a Column with it's annotation as a single structure.
#[derive(Debug, Clone)]
pub(super) struct DebugColumn {
    /// The type of the column.
    column_type: Any,
    /// The index of the column.
    index: usize,
    /// Annotation of the column
    annotation: String,
}

impl From<(Column, Option<&HashMap<Column, String>>)> for DebugColumn {
    fn from(info: (Column, Option<&HashMap<Column, String>>)) -> Self {
        DebugColumn {
            column_type: info.0.column_type,
            index: info.0.index,
            annotation: info
                .1
                .and_then(|map| map.get(&info.0))
                .cloned()
                .unwrap_or_default(),
        }
    }
}

impl fmt::Display for DebugColumn {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            f,
            "Column('{:?}', {} - {})",
            self.column_type, self.index, self.annotation
        )
    }
}

/// A "virtual cell" is a PLONK cell that has been queried at a particular relative offset
/// within a custom gate.
#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
pub struct VirtualCell {
    name: String,
    pub(super) column: Column,
    pub(super) rotation: i32,
}

impl From<(Column, i32)> for VirtualCell {
    fn from((column, rotation): (Column, i32)) -> Self {
        VirtualCell {
            name: "".to_string(),
            column,
            rotation,
        }
    }
}

impl<S: AsRef<str>> From<(S, Column, i32)> for VirtualCell {
    fn from((name, column, rotation): (S, Column, i32)) -> Self {
        VirtualCell {
            name: name.as_ref().to_string(),
            column,
            rotation,
        }
    }
}

impl From<plonk::VirtualCell> for VirtualCell {
    fn from(c: plonk::VirtualCell) -> Self {
        VirtualCell {
            name: "".to_string(),
            column: c.column.into(),
            rotation: c.rotation.0,
        }
    }
}

impl fmt::Display for VirtualCell {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}@{}", self.column, self.rotation)?;
        if !self.name.is_empty() {
            write!(f, "({})", self.name.as_str())?;
        }
        Ok(())
    }
}

/// Helper structure used to be able to inject Column annotations inside a `Display` or `Debug` call.
#[derive(Clone, Debug)]
pub(super) struct DebugVirtualCell {
    name: String,
    column: DebugColumn,
    rotation: i32,
}

impl From<(&VirtualCell, Option<&HashMap<Column, String>>)> for DebugVirtualCell {
    fn from(info: (&VirtualCell, Option<&HashMap<Column, String>>)) -> Self {
        DebugVirtualCell {
            name: info.0.name.clone(),
            column: DebugColumn::from((info.0.column, info.1)),
            rotation: info.0.rotation,
        }
    }
}

impl fmt::Display for DebugVirtualCell {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}@{}", self.column, self.rotation)?;
        if !self.name.is_empty() {
            write!(f, "({})", self.name)?;
        }
        Ok(())
    }
}

/// Metadata about a configured gate within a circuit.
#[derive(Debug, PartialEq, Eq, Clone)]
pub struct Gate {
    /// The index of the active gate. These indices are assigned in the order in which
    /// `ConstraintSystem::create_gate` is called during `Circuit::configure`.
    pub(super) index: usize,
    /// The name of the active gate. These are specified by the gate creator (such as
    /// a chip implementation), and is not enforced to be unique.
    pub(super) name: String,
}

impl fmt::Display for Gate {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "Gate {} ('{}')", self.index, self.name.as_str())
    }
}

impl<S: AsRef<str>> From<(usize, S)> for Gate {
    fn from((index, name): (usize, S)) -> Self {
        Gate {
            index,
            name: name.as_ref().to_string(),
        }
    }
}

/// Metadata about a configured constraint within a circuit.
#[derive(Debug, PartialEq, Eq, Clone)]
pub struct Constraint {
    /// The gate containing the constraint.
    pub(super) gate: Gate,
    /// The index of the polynomial constraint within the gate. These indices correspond
    /// to the order in which the constraints are returned from the closure passed to
    /// `ConstraintSystem::create_gate` during `Circuit::configure`.
    pub(super) index: usize,
    /// The name of the constraint. This is specified by the gate creator (such as a chip
    /// implementation), and is not enforced to be unique.
    pub(super) name: String,
}

impl fmt::Display for Constraint {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            f,
            "Constraint {}{} in gate {} ('{}')",
            self.index,
            if self.name.is_empty() {
                String::new()
            } else {
                format!(" ('{}')", self.name.as_str())
            },
            self.gate.index,
            self.gate.name,
        )
    }
}

impl<S: AsRef<str>> From<(Gate, usize, S)> for Constraint {
    fn from((gate, index, name): (Gate, usize, S)) -> Self {
        Constraint {
            gate,
            index,
            name: name.as_ref().to_string(),
        }
    }
}

/// Metadata about an assigned region within a circuit.
#[derive(Clone)]
pub struct Region {
    /// The index of the region. These indices are assigned in the order in which
    /// `Layouter::assign_region` is called during `Circuit::synthesize`.
    pub(super) index: usize,
    /// The name of the region. This is specified by the region creator (such as a chip
    /// implementation), and is not enforced to be unique.
    pub(super) name: String,
    /// A reference to the annotations of the Columns that exist within this `Region`.
    pub(super) column_annotations: Option<HashMap<ColumnMetadata, String>>,
}

impl Region {
    /// Fetch the annotation of a `Column` within a `Region` providing it's associated metadata.
    ///
    /// This function will return `None` if:
    /// - There's no annotation map generated for this `Region`.
    /// - There's no entry on the annotation map corresponding to the metadata provided.
    pub(crate) fn get_column_annotation(&self, metadata: ColumnMetadata) -> Option<String> {
        self.column_annotations
            .as_ref()
            .and_then(|map| map.get(&metadata).cloned())
    }
}

impl PartialEq for Region {
    fn eq(&self, other: &Self) -> bool {
        self.index == other.index && self.name == other.name
    }
}

impl Eq for Region {}

impl Debug for Region {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "Region {} ('{}')", self.index, self.name)
    }
}

impl fmt::Display for Region {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "Region {} ('{}')", self.index, self.name.as_str())
    }
}

impl From<(usize, String)> for Region {
    fn from((index, name): (usize, String)) -> Self {
        Region {
            index,
            name,
            column_annotations: None,
        }
    }
}

impl From<(usize, &str)> for Region {
    fn from((index, name): (usize, &str)) -> Self {
        Region {
            index,
            name: name.to_owned(),
            column_annotations: None,
        }
    }
}

impl From<(usize, String, HashMap<ColumnMetadata, String>)> for Region {
    fn from((index, name, annotations): (usize, String, HashMap<ColumnMetadata, String>)) -> Self {
        Region {
            index,
            name,
            column_annotations: Some(annotations),
        }
    }
}

impl From<(usize, &str, HashMap<ColumnMetadata, String>)> for Region {
    fn from((index, name, annotations): (usize, &str, HashMap<ColumnMetadata, String>)) -> Self {
        Region {
            index,
            name: name.to_owned(),
            column_annotations: Some(annotations),
        }
    }
}