/*
    Hurry Curry! - a game about cooking
    Copyright (C) 2025 Hurry Curry! Contributors

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as published by
    the Free Software Foundation, version 3 of the License only.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.

*/

use anyhow::Result;
use hurrycurry_protocol::{
    Gamedata, ItemIndex, Message, Recipe, RecipeIndex,
    book::{Diagram, DiagramEdge, DiagramNode, NodeStyle},
    glam::Vec2,
};
use hurrycurry_server::data::Serverdata;
use std::{
    cmp::Reverse,
    collections::{BTreeMap, BTreeSet, HashSet},
};

pub(crate) fn recipe_diagram(
    data: &Gamedata,
    serverdata: &Serverdata,
    target_items: &[&str],
) -> Result<Diagram> {
    let ambient_items = serverdata
        .initial_map
        .iter()
        .flat_map(|(_, (_, item))| item)
        .copied()
        .collect::<HashSet<_>>();

    let mut need = BTreeSet::from_iter(
        target_items
            .iter()
            .map(|name| data.get_item_by_name(name).unwrap()),
    );
    let mut have = BTreeSet::<ItemIndex>::new();
    let mut recipes = BTreeSet::new();

    #[derive(PartialEq, PartialOrd, Eq, Ord)]
    struct GraphRecipe {
        index: RecipeIndex,
        inputs: Vec<ItemIndex>,
        outputs: Vec<ItemIndex>,
    }

    while let Some(item) = need.pop_last() {
        for (ri, r) in data.recipes() {
            if r.outputs().contains(&item) {
                let gr = GraphRecipe {
                    inputs: r
                        .inputs()
                        .iter()
                        .filter(|i| !ambient_items.contains(i))
                        .copied()
                        .collect(),
                    outputs: r
                        .outputs()
                        .iter()
                        .filter(|i| !ambient_items.contains(i))
                        .copied()
                        .collect(),
                    index: ri,
                };
                need.extend(&gr.inputs);
                have.extend(&gr.outputs);
                recipes.insert(gr);
            }
        }
    }

    let mut diag = Diagram::default();
    let mut item_index = BTreeMap::new();
    for i in have {
        item_index.insert(i, diag.nodes.len());
        diag.nodes.push(DiagramNode {
            label: Message::Item(i),
            position: Vec2::ZERO,
            style: if target_items.contains(&data.item_name(i)) {
                NodeStyle::FinalProduct
            } else {
                NodeStyle::IntermediateProduct
            },
        });
    }
    for r in recipes {
        let index = diag.nodes.len();
        let recipe = data.recipe(r.index);

        if matches!(recipe, Recipe::Instant { .. }) && r.inputs.len() >= 1 && r.outputs.len() >= 1 {
            for i in r.inputs {
                diag.edges.push(DiagramEdge {
                    src: item_index[&i],
                    dst: item_index[&r.outputs[0]],
                    label: None,
                });
            }
            continue;
        }
        if matches!(recipe, Recipe::Passive { tile: None, .. })
            && r.inputs.len() == 1
            && r.outputs.len() == 1
        {
            diag.nodes[item_index[&r.inputs[0]]].style = NodeStyle::ProcessPassive;
            diag.edges.push(DiagramEdge {
                src: item_index[&r.inputs[0]],
                dst: item_index[&r.outputs[0]],
                label: None,
            });
            continue;
        }

        let (kind, style) = match recipe {
            Recipe::Passive { .. } => ("Passive", NodeStyle::ProcessPassive),
            Recipe::Active { .. } => ("Active", NodeStyle::ProcessActive),
            Recipe::Instant { .. } => ("Instant", NodeStyle::ProcessInstant),
        };
        diag.nodes.push(DiagramNode {
            position: Vec2::ZERO,
            label: if let Some(tile) = recipe.tile() {
                Message::Tile(tile)
            } else {
                Message::Text(kind.to_string())
            },
            style,
        });

        for i in r.inputs {
            diag.edges.push(DiagramEdge {
                src: item_index[&i],
                dst: index,
                label: None,
            });
        }
        for o in r.outputs {
            diag.edges.push(DiagramEdge {
                src: index,
                dst: item_index[&o],
                label: None,
            });
        }
    }

    merge_combine_clusters(&mut diag);
    remove_orphan_nodes(&mut diag);

    Ok(diag)
}

fn merge_combine_clusters(diag: &mut Diagram) {
    let instant_nodes = diag
        .nodes
        .iter()
        .enumerate()
        .filter(|(_, n)| matches!(n.style, NodeStyle::IntermediateProduct))
        .map(|(i, _)| i)
        .collect::<Vec<_>>();

    for ni in instant_nodes {
        let inputs = diag
            .edges
            .iter()
            .enumerate()
            .filter(|(_, e)| e.dst == ni)
            .map(|(i, e)| (i, e.src))
            .collect::<Vec<_>>();
        let outputs = diag
            .edges
            .iter()
            .enumerate()
            .filter(|(_, e)| e.src == ni)
            .map(|(i, e)| (i, e.dst))
            .collect::<Vec<_>>();

        if outputs
            .iter()
            .all(|&(_, ni)| diag.nodes[ni].style.is_procuct())
            && inputs
                .iter()
                .all(|&(_, ni)| diag.nodes[ni].style.is_procuct())
        {
            let mut to_remove = inputs
                .iter()
                .map(|&(i, _)| i)
                .chain(outputs.iter().map(|&(i, _)| i))
                .collect::<Vec<_>>();
            to_remove.sort_by_key(|x| Reverse(*x));
            for i in to_remove {
                diag.edges.remove(i);
            }

            for &input in &inputs {
                for &output in &outputs {
                    if !diag
                        .edges
                        .iter()
                        .any(|e| e.src == input.1 && e.dst == output.1)
                    {
                        diag.edges.push(DiagramEdge {
                            src: input.1,
                            dst: output.1,
                            label: None,
                        });
                    }
                }
            }
        }
    }
}

fn remove_orphan_nodes(diag: &mut Diagram) {
    let mut to_remove = diag
        .nodes
        .iter()
        .enumerate()
        .filter(|&(i, _)| !diag.edges.iter().any(|e| e.src == i || e.dst == i))
        .map(|(i, _)| i)
        .collect::<Vec<_>>();
    to_remove.sort_by_key(|x| Reverse(*x));

    for e in &mut diag.edges {
        e.src -= to_remove.iter().filter(|&&i| i < e.src).count();
        e.dst -= to_remove.iter().filter(|&&i| i < e.dst).count();
    }
    for i in to_remove {
        diag.nodes.remove(i);
    }
}