// Copyright (c) 2021-2021 Thomas Kramer.
// SPDX-FileCopyrightText: 2022 Thomas Kramer <code@tkramer.ch>
//
// SPDX-License-Identifier: AGPL-3.0-or-later

/// Implement the design rule traits from `libreda-db` for LEF.
/// This allows standardized read access to design-rules and technology data.
///
/// [`LEFDesignRuleAdapter`] creates the mapping between the layers defined in a layout and the layers defined in a LEF file
/// and then provides access to the LEF data via the technology traits.
use log;

use crate::common::Orient;
use crate::lef_ast;
use crate::lef_ast::{Layer, RoutingDirection, TechnologyLef, LEF};
use db::traits::*;
use libreda_db::prelude as db;
use libreda_db::technology::layerstack;
use libreda_db::technology::layerstack::{RoutingLayer, RoutingLayerStack, RoutingLayerType};
use libreda_db::technology::rules;
use libreda_db::technology::rules::RuleBase;
use num_traits::{FromPrimitive, ToPrimitive};
use std::collections::HashMap;
use std::marker::PhantomData;

/// Provides standardized read access to the design-rules defined in a LEF structure.
pub struct LEFDesignRuleAdapter<'a, L: db::LayoutBase> {
    /// Underlying LEF data.
    lef: &'a LEF,
    /// Data-base units per micron.
    dbu: f64,
    /// Mapping from layer IDs to actual LEF layer data.
    layer_mapping: HashMap<L::LayerId, &'a lef_ast::Layer>,
    /// Layers sorted by the processing order: Starts with layers close to the substrate, ends with top level metal layers.
    layer_stack: Vec<(L::LayerId, &'a lef_ast::Layer)>,
    ty: PhantomData<L>,
}

impl<'a, L> LEFDesignRuleAdapter<'a, L>
where
    L: db::LayoutBase,
    L::Coord: ToPrimitive, // Need to be able to cast a float into Coord.
{
    /// Convert from a distance in data-base units into a LEF distance (f64).
    fn db_distance_to_lef(&self, db_distance: L::Coord) -> f64 {
        let dbu = self.dbu;

        db_distance
            .to_f64()
            .expect("Conversion from LEF distance unit to database distance unit failed.")
            / dbu
    }
}

impl<'a, L> LEFDesignRuleAdapter<'a, L>
where
    L: db::LayoutBase,
    L::Coord: FromPrimitive, // Need to be able to cast a float into Coord.
{
    /// Convert from a LEF distance (f64) into the correct unit used by the layout.
    fn lef_distance_to_db(&self, lef_distance: f64) -> L::Coord {
        let dbu = self.dbu;

        L::Coord::from_f64(lef_distance * dbu)
            .expect("Conversion from LEF distance unit to database distance unit failed.")
    }
}

impl<'a, L> LEFDesignRuleAdapter<'a, L>
where
    L: db::LayoutBase,
    L::Coord: FromPrimitive + ToPrimitive, // Need to be able to cast a float into Coord.
{
    /// Create a new design rule adapter for a LEF data structure.
    /// Derives the mapping from layer IDs and LEF layers based on the layer names.
    pub fn new(lef: &'a LEF, layout: &L) -> Self {
        let dbu = layout
            .dbu()
            .to_f64()
            .expect("failed to convert data-base unit from to f64");
        Self::new_from_layer_mapping(lef, &Self::extract_layer_mapping_from_layout(layout), dbu)
    }

    /// Create a new design rule adapter for a LEF data structure
    /// with a custom mapping between layer names and layer IDs.
    pub fn new_from_layer_mapping(
        lef: &'a LEF,
        layer_ids_by_name: &HashMap<String, L::LayerId>,
        dbu: f64,
    ) -> Self {
        assert!(
            dbu > 0.0,
            "'data-base units per micron' must be larger than 0"
        );

        let mut new = Self {
            lef,
            dbu,
            layer_mapping: Default::default(),
            layer_stack: Default::default(),
            ty: Default::default(),
        };

        new.create_layer_mapping(layer_ids_by_name);

        new
    }

    /// Find the mapping from layer names to layer IDs.
    fn extract_layer_mapping_from_layout(layout: &L) -> HashMap<String, L::LayerId> {
        layout
            .each_layer()
            .filter_map(|layer_id| {
                let layer_name = layout
                    .layer_info(&layer_id)
                    .name
                    .as_ref()
                    .map(|n| n.to_string());
                layer_name.map(|name| (name, layer_id))
            })
            .collect()
    }

    /// Initialize the mapping: layer ID -> LEF layer structure.
    fn create_layer_mapping(&mut self, layer_ids_by_name: &HashMap<String, L::LayerId>) {
        // Create look-up table: Layer name -> LEF layer
        let lef_layers_by_name = self
            .lef
            .technology
            .layers
            .iter()
            .map(|layer| (layer.name(), layer));

        // Create look-up table: Layer ID -> LEF layer
        let lef_layers_by_layer_id: Vec<_> = lef_layers_by_name
            .filter_map(|(layer_name, layer)| {
                let layer_id = layer_ids_by_name.get(layer_name);
                layer_id.map(|id| (id.clone(), layer))
            })
            .collect();

        self.layer_mapping = lef_layers_by_layer_id.iter().cloned().collect();

        self.layer_stack = lef_layers_by_layer_id;
    }
}

impl<'a, L: db::LayoutBase> layerstack::RoutingLayerStack for LEFDesignRuleAdapter<'a, L> {
    fn layer_stack(&self) -> Vec<RoutingLayer<Self::LayerId>> {
        self.layer_stack
            .iter()
            // Take routing and cut layers only.
            .filter_map(|(id, layer)| match layer {
                Layer::MasterSlice(_) => None,
                Layer::Cut(_) => Some(RoutingLayer::new(id.clone(), RoutingLayerType::Cut)),
                Layer::Routing(_) => Some(RoutingLayer::new(id.clone(), RoutingLayerType::Routing)),
            })
            .collect()
    }
}

impl<'a, L: db::LayoutBase> rules::RuleBase for LEFDesignRuleAdapter<'a, L> {
    type LayerId = L::LayerId;
}

impl<'a, L: db::LayoutBase> rules::DistanceRuleBase for LEFDesignRuleAdapter<'a, L> {
    type Distance = L::Coord;
    type Area = L::Coord;
}

impl<'a, L: db::LayoutBase> rules::MinimumSpacing for LEFDesignRuleAdapter<'a, L>
where
    L::Coord: ToPrimitive + FromPrimitive,
{
    fn min_spacing_absolute(&self, layer_id: &Self::LayerId) -> Option<Self::Distance> {
        self.layer_mapping
            .get(layer_id)
            .and_then(|layer| match layer {
                Layer::MasterSlice(_) => unimplemented!("Min spacing for MASTERSLICE layers."),
                Layer::Cut(_) => {
                    // log::warn!("Not implemented: minimum spacing for CUT layers.");
                    // TODO: minimum spacing for CUT layers
                    None
                }
                Layer::Routing(routing_layer) => {
                    // Get spacing based on routing_layer.spacing_table or routing_layer.spacing.
                    get_absolute_min_spacing_of_routing_layer(routing_layer)
                }
            })
            .map(|d| self.lef_distance_to_db(d))
    }

    fn min_spacing(
        &self,
        layer_id: &Self::LayerId,
        run_length: Self::Distance,
        width: Self::Distance,
    ) -> Option<Self::Distance> {
        let run_length = self.db_distance_to_lef(run_length);
        let width = self.db_distance_to_lef(width);

        self.layer_mapping
            .get(layer_id)
            .and_then(|layer| match layer {
                Layer::MasterSlice(_) => unimplemented!("Min spacing for MASTERSLICE layers."),
                Layer::Cut(_) => {
                    // TODO: unimplemented!("Min spacing for CUT layers.");
                    None
                }
                Layer::Routing(routing_layer) => {
                    // Get spacing based on routing_layer.spacing_table or routing_layer.spacing.
                    get_min_spacing_of_routing_layer(routing_layer, run_length, width)
                }
            })
            .map(|d| self.lef_distance_to_db(d))
    }
}

impl<'a, L: db::LayoutBase> rules::PreferredRoutingDirection for LEFDesignRuleAdapter<'a, L>
where
    L::Coord: ToPrimitive + FromPrimitive,
{
    fn preferred_routing_direction(&self, layer_id: &Self::LayerId) -> Option<db::Orientation2D> {
        self.layer_mapping
            .get(layer_id) // Find LEF layer.
            .and_then(|layer| match layer {
                Layer::Routing(routing_layer) => {
                    match routing_layer.direction {
                        RoutingDirection::Vertical => Some(db::Orientation2D::Vertical),
                        RoutingDirection::Horizontal => Some(db::Orientation2D::Horizontal),
                        RoutingDirection::Diag45 => {
                            // TODO
                            None
                        }
                        RoutingDirection::Diag135 => {
                            // TODO
                            None
                        }
                    }
                }
                _ => None, // No preferred routing direction for other layer types.
            })
    }
}

impl<'a, L> rules::RoutingRules for LEFDesignRuleAdapter<'a, L>
where
    L: db::LayoutBase,
    L::Coord: ToPrimitive + FromPrimitive,
{
    fn default_pitch(&self, layer_id: &Self::LayerId) -> Option<(Self::Distance, Self::Distance)> {
        self.layer_mapping
            .get(layer_id)
            .and_then(|layer| match layer {
                Layer::MasterSlice(_) => unimplemented!("Default pitch for MASTERSLICE layers."),
                Layer::Cut(_) => None, // TODO
                Layer::Routing(routing_layer) => Some(routing_layer.pitch),
            })
            .map(|(pitch_x, pitch_y)| {
                (
                    self.lef_distance_to_db(pitch_x),
                    self.lef_distance_to_db(pitch_y),
                )
            })
    }
}

/// Get the minimal spacing on the given layer.
/// Return `None` if there's no spacing rule defined.
/// TODO: Currently only SPACINGTABLEs are considered. Also support SPACING statements.
fn get_absolute_min_spacing_of_routing_layer(routing_layer: &lef_ast::RoutingLayer) -> Option<f64> {
    if let Some(spacing_table) = &routing_layer.spacing_table {
        spacing_table
            .spacings
            .first()
            .and_then(|spacings| spacings.first())
            .copied()
            .or(Some(0.))
    } else {
        // Derive spacing from SPACING statements.
        routing_layer
            .spacing
            .iter()
            .map(|spacing_rule| spacing_rule.min_spacing)
            // Find minimum.
            .reduce(|min, x| if x < min { x } else { min })
    }
}

/// Get the minimal spacing on the given layer.
/// Return `None` if there's no spacing rule defined.
/// TODO: Currently only SPACINGTABLEs are considered. Also support SPACING statements.
fn get_min_spacing_of_routing_layer(
    routing_layer: &lef_ast::RoutingLayer,
    parallel_runlength: f64,
    width: f64,
) -> Option<f64> {
    if let Some(spacing_table) = &routing_layer.spacing_table {
        // Find correct row for the given width.
        let row = spacing_table
            .spacings
            .iter()
            .zip(&spacing_table.widths)
            .filter(|(row, &w)| w <= width)
            .last()
            .map(|(row, _)| row);
        row.and_then(|row| {
            // Find correct value based on the runlength.
            row.iter()
                .zip(&spacing_table.parallel_run_lengths)
                .filter(|(spacing, &run_length)| run_length <= parallel_runlength)
                .last()
                .map(|(&spacing, _)| spacing)
        })
    } else {
        // TODO: Derive spacing from SPACING statements.
        get_absolute_min_spacing_of_routing_layer(routing_layer)
    }
}

impl<'a, L> rules::MinimumWidth for LEFDesignRuleAdapter<'a, L>
where
    L: db::LayoutBase,
    L::Coord: FromPrimitive,
{
    fn min_width(
        &self,
        layer_id: &Self::LayerId,
        shape_length: Option<Self::Distance>,
    ) -> Option<Self::Distance> {
        self.layer_mapping
            .get(layer_id)
            .and_then(|layer| match layer {
                Layer::MasterSlice(_) => {
                    unimplemented!("Minimum width for LEF 'masterslice' layers is not implemented.")
                }
                Layer::Cut(_) => {
                    None
                    // TODO unimplemented!("Minimum width for LEF 'cut' layers is not implemented.")
                }
                Layer::Routing(routing_layer) => routing_layer.min_width,
            })
            .map(|d| self.lef_distance_to_db(d))
    }
}

impl<'a, L> rules::DefaultWidth for LEFDesignRuleAdapter<'a, L>
where
    L: db::LayoutBase,
    L::Coord: FromPrimitive,
{
    fn default_width(
        &self,
        layer_id: &Self::LayerId,
        shape_length: Option<Self::Distance>,
    ) -> Option<Self::Distance> {
        self.layer_mapping
            .get(layer_id)
            .and_then(|layer| match layer {
                Layer::MasterSlice(_) => {
                    unimplemented!("Default width for LEF 'masterslice' layers is not implemented.")
                }
                Layer::Cut(_) => {
                    None
                    // TODO: unimplemented!("Default width for LEF 'cut' layers is not implemented.")
                }
                Layer::Routing(routing_layer) => Some(routing_layer.width),
            })
            .map(|d| self.lef_distance_to_db(d))
    }
}

#[cfg(test)]
mod tests {
    use crate::lef_parser::read_lef_chars;
    use crate::lef_tech_adapter::LEFDesignRuleAdapter;
    use db::technology::rules::*;
    use db::traits::*;
    use libreda_db::prelude as db;

    const LEF_DATA: &'static str = r#"
VERSION 5.5 ;
NAMESCASESENSITIVE ON ;
BUSBITCHARS "[]" ;
DIVIDERCHAR "/" ;

PROPERTYDEFINITIONS
  LAYER contactResistance REAL ;
END PROPERTYDEFINITIONS

UNITS
  DATABASE MICRONS 1000 ;
END UNITS
MANUFACTURINGGRID 0.0025 ;
LAYER poly
  TYPE MASTERSLICE ;
END poly

LAYER contact
  TYPE CUT ;
  SPACING 0.075 ;
  PROPERTY contactResistance 10.5 ;
END contact

LAYER metal1
  TYPE ROUTING ;
  DIRECTION HORIZONTAL ;
  PITCH 0.19 ;
  WIDTH 0.065 ;
  MINWIDTH 0.05 ;
  SPACING 0.065 ;
  RESISTANCE RPERSQ 0.38 ;

  SPACINGTABLE
    PARALLELRUNLENGTH   0.0  1.0
    WIDTH 0.0           0.1  0.3
    WIDTH 0.5           0.4  0.5
  ;

END metal1

LAYER via1
  TYPE CUT ;
  SPACING 0.075 ;
  PROPERTY contactResistance 5.69 ;
END via1

LAYER metal2
    TYPE ROUTING ;
    DIRECTION VERTICAL ;
    PITCH 0.19 ;
    WIDTH 0.07 ;
    SPACING 0.075 ;
END metal2

LAYER OVERLAP
  TYPE OVERLAP ;
END OVERLAP

VIA M2_M1_via DEFAULT
  LAYER metal1 ;
    RECT -0.0675 -0.0325 0.0675 0.0325 ;
  LAYER via1 ;
    RECT -0.0325 -0.0325 0.0325 0.0325 ;
  LAYER metal2 ;
    RECT -0.035 -0.0675 0.035 0.0675 ;
END M2_M1_via

VIARULE M2_M1 GENERATE
  LAYER metal1 ;
    ENCLOSURE 0 0.035 ;
  LAYER metal2 ;
    ENCLOSURE 0 0.035 ;
  LAYER via1 ;
    RECT -0.0325 -0.0325 0.0325 0.0325 ;
    SPACING 0.14 BY 0.14 ;
END M2_M1

VIARULE M1_POLY GENERATE
  LAYER poly ;
    ENCLOSURE 0 0 ;
  LAYER metal1 ;
    ENCLOSURE 0 0.035 ;
  LAYER contact ;
    RECT -0.0325 -0.0325 0.0325 0.0325 ;
    SPACING 0.14 BY 0.14 ;
END M1_POLY

SPACING
  SAMENET metal1 metal1 0.065 ;
  SAMENET metal2 metal2 0.07 ;
  SAMENET metal6 metal6 0.14 ;
  SAMENET metal5 metal5 0.14 ;
  SAMENET metal4 metal4 0.14 ;
  SAMENET metal3 metal3 0.07 ;
  SAMENET metal7 metal7 0.4 ;
  SAMENET metal8 metal8 0.4 ;
  SAMENET metal9 metal9 0.8 ;
  SAMENET metal10 metal10 0.8 ;
END SPACING

END LIBRARY

    "#;

    fn create_empty_layout() -> (db::Chip, Vec<<db::Chip as db::LayoutIds>::LayerId>) {
        // Create an empty layout with some layers which match the LEF layer names.
        let mut layout = db::Chip::new();
        layout.set_dbu(1000);

        let layer1 = layout.create_layer(1, 0);
        layout.set_layer_name(&layer1, Some("metal1".into()));

        let layer2 = layout.create_layer(2, 0);
        layout.set_layer_name(&layer2, Some("metal2".into()));

        (layout, vec![layer1, layer2])
    }

    #[test]
    fn test_lef_rule_adapter_pitch() {
        let lef = read_lef_chars(LEF_DATA.chars()).expect("Failed to parse LEF");

        let (layout, layers) = create_empty_layout();
        let layer1 = &layers[0];

        let rules = LEFDesignRuleAdapter::new(&lef, &layout);

        dbg!(rules.layer_mapping[layer1]);

        // Try to fetch design rules.
        assert_eq!(rules.default_pitch(layer1), Some((190, 190)));
        assert_eq!(rules.default_pitch_preferred_direction(layer1), Some(190));
    }

    #[test]
    fn test_lef_rule_adapter_min_width() {
        let lef = read_lef_chars(LEF_DATA.chars()).expect("Failed to parse LEF");

        let (layout, layers) = create_empty_layout();
        let layer1 = &layers[0];

        let rules = LEFDesignRuleAdapter::new(&lef, &layout);

        dbg!(rules.layer_mapping[layer1]);

        // Try to fetch design rules.
        assert_eq!(rules.min_width(layer1, None), Some(50));
    }

    #[test]
    fn test_lef_rule_adapter_default_width() {
        let lef = read_lef_chars(LEF_DATA.chars()).expect("Failed to parse LEF");

        let (layout, layers) = create_empty_layout();
        let layer1 = &layers[0];

        let rules = LEFDesignRuleAdapter::new(&lef, &layout);

        dbg!(rules.layer_mapping[layer1]);

        // Try to fetch design rules.
        assert_eq!(rules.default_width(layer1, None), Some(65));
    }

    #[test]
    fn test_lef_rule_adapter_spacing_table() {
        let lef = read_lef_chars(LEF_DATA.chars()).expect("Failed to parse LEF");

        let (layout, layers) = create_empty_layout();
        let layer1 = &layers[0];
        let layer2 = &layers[1];

        let rules = LEFDesignRuleAdapter::new(&lef, &layout);

        // Try to fetch design rules.

        assert_eq!(rules.min_spacing_absolute(layer1), Some(100));

        assert_eq!(rules.min_spacing(layer1, 0, 0), Some(100));

        assert_eq!(rules.min_spacing(layer1, 999, 0), Some(100));
        assert_eq!(rules.min_spacing(layer1, 1000, 0), Some(300));

        assert_eq!(rules.min_spacing(layer1, 0, 499), Some(100));
        assert_eq!(rules.min_spacing(&layer1, 0, 500), Some(400));
    }

    #[test]
    fn test_lef_rule_adapter_min_spacing() {
        let lef = read_lef_chars(LEF_DATA.chars()).expect("Failed to parse LEF");

        let (layout, layers) = create_empty_layout();
        let layer1 = &layers[0];
        let layer2 = &layers[1];

        let rules = LEFDesignRuleAdapter::new(&lef, &layout);

        dbg!(rules.layer_mapping[layer2]);

        // Spacing rules on metal2 without SPACINGTABLE
        assert_eq!(rules.min_spacing(layer2, 0, 0), Some(75));
        assert_eq!(rules.min_spacing_absolute(layer2), Some(75));
    }
}