use std::borrow::Cow;
use std::collections::HashMap;
use std::collections::HashSet;

use css_module_lexer::Dependency;
use css_module_lexer::LexDependencies;
use css_module_lexer::Lexer;
use css_module_lexer::Mode;
use css_module_lexer::Range;
use css_module_lexer::Warning;
use css_module_lexer::WarningKind;
use indoc::indoc;
use linked_hash_map::LinkedHashMap;

#[derive(Debug, Default, Clone, Hash, PartialEq, Eq)]
pub struct ExtractImports;

enum StateMarker {
    Permanent,
    Temporary,
}

fn add_import_to_graph<'import>(
    import: &'import str,
    rule_index: u32,
    graph: &mut LinkedHashMap<&'import str, Vec<&'import str>>,
    visited: &mut HashSet<String>,
    siblings: &mut HashMap<u32, Vec<&'import str>>,
) {
    let visited_id = format!("{rule_index}_{import}");
    if visited.contains(&visited_id) {
        return;
    }
    let children = graph.entry(import).or_default();
    if let Some(siblings) = siblings.get(&rule_index) {
        children.extend(siblings);
    }
    visited.insert(visited_id);
    siblings.entry(rule_index).or_default().push(import);
}

fn walk_graph<'import>(
    import: &'import str,
    graph: &LinkedHashMap<&'import str, Vec<&'import str>>,
    state: &mut HashMap<&'import str, StateMarker>,
    result: &mut Vec<&'import str>,
    warnings: &mut Vec<Warning<'import>>,
) {
    if let Some(marker) = state.get(import) {
        match marker {
            StateMarker::Permanent => {
                return;
            }
            StateMarker::Temporary => {
                warnings.push(Warning::new(
                    Range::new(0, 0),
                    WarningKind::Unexpected {
                        message: "Failed to resolve order of composed modules",
                    },
                ));
                return;
            }
        }
    }
    state.insert(import, StateMarker::Temporary);
    for child in &graph[import] {
        walk_graph(child, graph, state, result, warnings);
    }
    state.insert(import, StateMarker::Permanent);
    result.push(import);
}

fn topological_sort<'import>(
    graph: &LinkedHashMap<&'import str, Vec<&'import str>>,
    warnings: &mut Vec<Warning<'import>>,
) -> Vec<&'import str> {
    let mut result = Vec::new();
    let mut state = HashMap::new();
    for import in graph.keys() {
        walk_graph(import, graph, &mut state, &mut result, warnings);
    }
    result
}

impl ExtractImports {
    pub fn transform<'s>(&self, input: &'s str) -> (String, Vec<Warning<'s>>) {
        let mut imported = String::new();
        let mut result = String::new();
        let mut warnings = Vec::new();
        let mut index = 0;
        let mut lexer = Lexer::new(input);
        let mut composes_contents = Vec::new();
        let mut postfix = 0;
        let mut imports: LinkedHashMap<&str, LinkedHashMap<&str, Cow<str>>> = LinkedHashMap::new();
        let mut rule_index = 0;
        let mut graph: LinkedHashMap<&str, Vec<&str>> = LinkedHashMap::new();
        let mut visited = HashSet::new();
        let mut siblings = HashMap::new();
        let mut visitor = LexDependencies::new(
            |dependency| match dependency {
                Dependency::LocalClass { .. } | Dependency::LocalId { .. } => {
                    rule_index += 1;
                }
                Dependency::Composes { names, from, .. } => {
                    let mut composes_content = String::new();
                    if let Some(from) = from {
                        if from == "global" {
                            for i in 0..names.len() {
                                let name = names[i];
                                composes_content += "global(";
                                composes_content += name;
                                composes_content += ")";
                                if i + 1 != names.len() {
                                    composes_content += " ";
                                }
                            }
                        } else {
                            let path = from.trim_matches(|c| c == '\'' || c == '"');
                            add_import_to_graph(
                                path,
                                rule_index,
                                &mut graph,
                                &mut visited,
                                &mut siblings,
                            );
                            let values = imports.entry(path).or_default();
                            for i in 0..names.len() {
                                let name = names[i];
                                if let Some(value) = values.get(name) {
                                    composes_content += &value;
                                } else {
                                    let value = format!(
                                        "i__imported_{}_{postfix}",
                                        name.replace(
                                            |c: char| !c.is_ascii_alphanumeric() && c != '_',
                                            "_"
                                        )
                                    );
                                    postfix += 1;
                                    composes_content += &value;
                                    values.insert(name, value.into());
                                }
                                if i + 1 != names.len() {
                                    composes_content += " ";
                                }
                            }
                        }
                    } else {
                        for i in 0..names.len() {
                            let name = names[i];
                            composes_content += name;
                            if i + 1 != names.len() {
                                composes_content += " ";
                            }
                        }
                    }
                    composes_contents.push(composes_content);
                }
                Dependency::Replace { content, range } => {
                    if !composes_contents.is_empty() {
                        let composes_contents = std::mem::take(&mut composes_contents);
                        result +=
                            Lexer::slice_range(input, &Range::new(index, range.start)).unwrap();
                        result += "composes: ";
                        result += &composes_contents.join(", ");
                        result += ";";
                        index = range.end;
                    } else {
                        let original = Lexer::slice_range(input, &range).unwrap();
                        if original.starts_with(":export") || original.starts_with(":import(") {
                            result +=
                                Lexer::slice_range(input, &Range::new(index, range.start)).unwrap();
                            result += content;
                            index = range.end;
                        }
                    }
                }
                Dependency::ICSSImportFrom { path } => {
                    let path = path.trim_matches(|c| c == '\'' || c == '"');
                    imports.insert(path, LinkedHashMap::new());
                    add_import_to_graph(path, rule_index, &mut graph, &mut visited, &mut siblings);
                }
                Dependency::ICSSImportValue { prop, value } => {
                    let (_, values) = imports.iter_mut().last().unwrap();
                    values.insert(value, prop.into());
                }
                _ => {}
            },
            |warning| warnings.push(warning),
            Mode::Local,
        );
        lexer.lex(&mut visitor);
        let len = input.len() as u32;
        if index != len {
            result += Lexer::slice_range(input, &Range::new(index, len)).unwrap();
        }
        let order = topological_sort(&graph, &mut warnings);
        for import in order {
            let values = &imports[import];
            imported += ":import(\"";
            imported += import;
            imported += "\") {\n";
            for (value, prop) in values {
                imported += "    ";
                imported += &prop;
                imported += ": ";
                imported += value;
                imported += ";\n";
            }
            imported += "}\n";
        }
        (imported + result.trim_start(), warnings)
    }
}

fn test(input: &str, expected: &str) {
    let (actual, warnings) = ExtractImports::default().transform(input);
    assert!(warnings.is_empty(), "{}", &warnings[0]);
    similar_asserts::assert_eq!(expected, actual);
}

fn test_with_warning(input: &str, expected: &str, warning: &str) {
    let (actual, warnings) = ExtractImports::default().transform(input);
    assert!(
        warnings[0].to_string().contains(warning),
        "{}",
        &warnings[0]
    );
    similar_asserts::assert_eq!(expected, actual);
}

#[test]
fn composing_globals() {
    test(
        ":local(.exportName) { composes: importName secondImport from global; other: rule; }",
        ":local(.exportName) { composes: global(importName) global(secondImport); other: rule; }",
    );
}

#[test]
fn existing_import() {
    test(
        indoc! {r#"
            :import("path/library.css") {
                something: else;
            }
            :local(.exportName) {
                composes: importName from 'path/library.css';
            }
        "#},
        indoc! {r#"
            :import("path/library.css") {
                something: else;
                i__imported_importName_0: importName;
            }
            :local(.exportName) {
                composes: i__imported_importName_0;
            }
        "#},
    );
}

#[test]
fn import_comment() {
    test(
        indoc! {r#"
            /*
            :local(.exportName) {
                composes: importName from "path/library.css";
                other: rule;
            }
            */
        "#},
        indoc! {r#"
            /*
            :local(.exportName) {
                composes: importName from "path/library.css";
                other: rule;
            }
            */
        "#},
    );
}

#[test]
fn import_consolidate() {
    test(
        indoc! {r#"
            :local(.exportName) {
                composes: importName secondImport from 'path/library.css';
                other: rule;
            }
            :local(.otherExport) {
                composes: thirdImport from 'path/library.css';
                composes: otherLibImport from 'path/other-lib.css';
            }
        "#},
        indoc! {r#"
            :import("path/library.css") {
                i__imported_importName_0: importName;
                i__imported_secondImport_1: secondImport;
                i__imported_thirdImport_2: thirdImport;
            }
            :import("path/other-lib.css") {
                i__imported_otherLibImport_3: otherLibImport;
            }
            :local(.exportName) {
                composes: i__imported_importName_0 i__imported_secondImport_1;
                other: rule;
            }
            :local(.otherExport) {
                composes: i__imported_thirdImport_2;
                composes: i__imported_otherLibImport_3;
            }
        "#},
    );
}

#[test]
fn import_local_extends() {
    test(
        indoc! {r#"
            :local(.exportName) {
                composes: localName;
                other: rule;
            }
        "#},
        indoc! {r#"
            :local(.exportName) {
                composes: localName;
                other: rule;
            }
        "#},
    );
}

#[test]
fn import_media() {
    test(
        indoc! {r#"
            @media screen {
                :local(.exportName) {
                    composes: importName from "path/library.css";
                    composes: importName2 from "path/library.css";
                    other: rule2;
                }
            }

            :local(.exportName) {
                composes: importName from "path/library.css";
                other: rule;
            }
        "#},
        indoc! {r#"
            :import("path/library.css") {
                i__imported_importName_0: importName;
                i__imported_importName2_1: importName2;
            }
            @media screen {
                :local(.exportName) {
                    composes: i__imported_importName_0;
                    composes: i__imported_importName2_1;
                    other: rule2;
                }
            }

            :local(.exportName) {
                composes: i__imported_importName_0;
                other: rule;
            }
        "#},
    );
}

#[test]
fn import_multiple_classes() {
    test(
        ":local(.exportName) { composes: importName secondImport from 'path/library.css'; other: rule; }\n",
        indoc! {r#"
            :import("path/library.css") {
                i__imported_importName_0: importName;
                i__imported_secondImport_1: secondImport;
            }
            :local(.exportName) { composes: i__imported_importName_0 i__imported_secondImport_1; other: rule; }
        "#},
    );
}

#[test]
fn import_multiple_references() {
    test(
        indoc! {r#"
            :local(.exportName) {
                composes: importName secondImport from 'path/library.css';
                composes: importName from 'path/library2.css';
                composes: importName2 from 'path/library.css';
            }
            :local(.exportName2) {
                composes: secondImport from 'path/library.css';
                composes: secondImport from 'path/library.css';
                composes: thirdDep from 'path/dep3.css';
            }
        "#},
        indoc! {r#"
            :import("path/library.css") {
                i__imported_importName_0: importName;
                i__imported_secondImport_1: secondImport;
                i__imported_importName2_3: importName2;
            }
            :import("path/library2.css") {
                i__imported_importName_2: importName;
            }
            :import("path/dep3.css") {
                i__imported_thirdDep_4: thirdDep;
            }
            :local(.exportName) {
                composes: i__imported_importName_0 i__imported_secondImport_1;
                composes: i__imported_importName_2;
                composes: i__imported_importName2_3;
            }
            :local(.exportName2) {
                composes: i__imported_secondImport_1;
                composes: i__imported_secondImport_1;
                composes: i__imported_thirdDep_4;
            }
        "#},
    );
}

#[test]
fn import_only_whitelist() {
    test(
        ":local(.exportName) { imports: importName from \"path/library.css\"; something-else: otherLibImport from \"path/other-lib.css\"; }",
        ":local(.exportName) { imports: importName from \"path/library.css\"; something-else: otherLibImport from \"path/other-lib.css\"; }",
    );
}

#[test]
fn import_preserving_order() {
    test(
        indoc! {r#"
            .a {
                composes: b from "./b.css";
                composes: c from "./c.css";
                color: #aaa;
            }
        "#},
        indoc! {r#"
            :import("./b.css") {
                i__imported_b_0: b;
            }
            :import("./c.css") {
                i__imported_c_1: c;
            }
            .a {
                composes: i__imported_b_0;
                composes: i__imported_c_1;
                color: #aaa;
            }
        "#},
    );
}

#[test]
fn import_single_quotes() {
    test(
        indoc! {r#"
            :local(.exportName) {
                composes: importName from 'path/library.css';
                other: rule;
            }
        "#},
        indoc! {r#"
            :import("path/library.css") {
                i__imported_importName_0: importName;
            }
            :local(.exportName) {
                composes: i__imported_importName_0;
                other: rule;
            }
        "#},
    );
}

#[test]
fn import_spacing() {
    test(
        indoc! {r#"
            :local(.exportName) {
                composes: importName  from   	"path/library.css";
                composes: importName2 from   	"path/library.css";
                composes: importName   importName2   from   "path/library.css";
                other: rule;
            }
        "#},
        indoc! {r#"
            :import("path/library.css") {
                i__imported_importName_0: importName;
                i__imported_importName2_1: importName2;
            }
            :local(.exportName) {
                composes: i__imported_importName_0;
                composes: i__imported_importName2_1;
                composes: i__imported_importName_0 i__imported_importName2_1;
                other: rule;
            }
        "#},
    );
}

#[test]
fn import_within() {
    test(
        indoc! {r#"
            :local(.exportName) {
                composes: importName from "path/library.css";
                other: rule;
            }
        "#},
        indoc! {r#"
            :import("path/library.css") {
                i__imported_importName_0: importName;
            }
            :local(.exportName) {
                composes: i__imported_importName_0;
                other: rule;
            }
        "#},
    );
}

#[test]
fn multiple_composes() {
    test(
        indoc! {r#"
            :local(.exportName) {
                composes: importName from "path/library.css", beforeName from global, importName secondImport from global, firstImport secondImport from "path/library.css";
                other: rule;
            }

            :local(.duplicate) {
                composes: a from "./aa.css", b from "./bb.css", c from "./cc.css", a from "./aa.css", c from "./cc.css";
            }

            :local(.spaces) {
                composes: importName importName2 from "path/library.css", importName3 importName4 from "path/library.css";
            }

            :local(.unknown) {
                composes: foo bar, baz;
            }
        "#},
        indoc! {r#"
            :import("path/library.css") {
                i__imported_importName_0: importName;
                i__imported_firstImport_1: firstImport;
                i__imported_secondImport_2: secondImport;
                i__imported_importName2_6: importName2;
                i__imported_importName3_7: importName3;
                i__imported_importName4_8: importName4;
            }
            :import("./aa.css") {
                i__imported_a_3: a;
            }
            :import("./bb.css") {
                i__imported_b_4: b;
            }
            :import("./cc.css") {
                i__imported_c_5: c;
            }
            :local(.exportName) {
                composes: i__imported_importName_0, global(beforeName), global(importName) global(secondImport), i__imported_firstImport_1 i__imported_secondImport_2;
                other: rule;
            }

            :local(.duplicate) {
                composes: i__imported_a_3, i__imported_b_4, i__imported_c_5, i__imported_a_3, i__imported_c_5;
            }

            :local(.spaces) {
                composes: i__imported_importName_0 i__imported_importName2_6, i__imported_importName3_7 i__imported_importName4_8;
            }

            :local(.unknown) {
                composes: foo bar, baz;
            }
        "#},
    );
}

#[test]
fn nesting() {
    test_with_warning(
        indoc! {r#"
            :local(.foo) {
                display: grid;

                @media (orientation: landscape) {
                    &:local(.bar) {
                        grid-auto-flow: column;

                        @media (min-width: 1024px) {
                            &:local(.baz) {
                                composes: importName from "path/library.css";
                            }
                        }
                    }
                }
            }
        "#},
        indoc! {r#"
            :local(.foo) {
                display: grid;
            
                @media (orientation: landscape) {
                    &:local(.bar) {
                        grid-auto-flow: column;

                        @media (min-width: 1024px) {
                            &:local(.baz) {
                                composes: importName from "path/library.css";
                            }
                        }
                    }
                }
            }
        "#},
        "Composition is not allowed in nested rule",
    );
}

#[test]
fn resolve_composes_order() {
    test(
        indoc! {r#"
            .a {
                composes: c from "./c.css";
                color: #bebebe;
            }

            .b {
                /* `b` should be after `c` */
                composes: b from "./b.css";
                composes: c from "./c.css";
                color: #aaa;
            }
        "#},
        indoc! {r#"
            :import("./b.css") {
                i__imported_b_1: b;
            }
            :import("./c.css") {
                i__imported_c_0: c;
            }
            .a {
                composes: i__imported_c_0;
                color: #bebebe;
            }

            .b {
                /* `b` should be after `c` */
                composes: i__imported_b_1;
                composes: i__imported_c_0;
                color: #aaa;
            }
        "#},
    );
}

#[test]
fn resolve_duplicates() {
    test(
        indoc! {r#"
            :import("./cc.css") {
                smthing: somevalue;
            }

            .a {
                composes: a from './aa.css';
                composes: b from './bb.css';
                composes: c from './cc.css';
                composes: a from './aa.css';
                composes: c from './cc.css';
            }
        "#},
        indoc! {r#"
            :import("./aa.css") {
                i__imported_a_0: a;
            }
            :import("./bb.css") {
                i__imported_b_1: b;
            }
            :import("./cc.css") {
                smthing: somevalue;
                i__imported_c_2: c;
            }
            .a {
                composes: i__imported_a_0;
                composes: i__imported_b_1;
                composes: i__imported_c_2;
                composes: i__imported_a_0;
                composes: i__imported_c_2;
            }
        "#},
    );
}

#[test]
fn resolve_imports_order() {
    test(
        indoc! {r#"
            :import("custom-path.css") {
                /* empty to check the order */
            }

            :import("./bb.css") {
                somevalue: localvalue;
            }

            .a {
                composes: aa from './aa.css';
            }

            .b {
                composes: bb from './bb.css';
                composes: bb from './aa.css';
            }

            .c {
                composes: cc from './cc.css';
                composes: cc from './aa.css';
            }

            .d {
                composes: dd from './cc.css';
                composes: dd from './bb.css';
                composes: dd from './dd.css';
            }
        "#},
        indoc! {r#"
            :import("custom-path.css") {
            }
            :import("./cc.css") {
                i__imported_cc_3: cc;
                i__imported_dd_5: dd;
            }
            :import("./bb.css") {
                somevalue: localvalue;
                i__imported_bb_1: bb;
                i__imported_dd_6: dd;
            }
            :import("./aa.css") {
                i__imported_aa_0: aa;
                i__imported_bb_2: bb;
                i__imported_cc_4: cc;
            }
            :import("./dd.css") {
                i__imported_dd_7: dd;
            }
            .a {
                composes: i__imported_aa_0;
            }

            .b {
                composes: i__imported_bb_1;
                composes: i__imported_bb_2;
            }

            .c {
                composes: i__imported_cc_3;
                composes: i__imported_cc_4;
            }

            .d {
                composes: i__imported_dd_5;
                composes: i__imported_dd_6;
                composes: i__imported_dd_7;
            }
        "#},
    );
}

#[test]
fn valid_characters() {
    test(
        indoc! {r#"
            :local(.exportName) {
                composes: a -b --c _d from "path/library.css";
                composes: a_ b- c-- d\% from "path/library2.css";
            }
        "#},
        indoc! {r#"
            :import("path/library.css") {
                i__imported_a_0: a;
                i__imported__b_1: -b;
                i__imported___c_2: --c;
                i__imported__d_3: _d;
            }
            :import("path/library2.css") {
                i__imported_a__4: a_;
                i__imported_b__5: b-;
                i__imported_c___6: c--;
                i__imported_d___7: d\%;
            }
            :local(.exportName) {
                composes: i__imported_a_0 i__imported__b_1 i__imported___c_2 i__imported__d_3;
                composes: i__imported_a__4 i__imported_b__5 i__imported_c___6 i__imported_d___7;
            }
        "#},
    );
}

#[test]
fn check_import_order() {
    test_with_warning(
        indoc! {r#"
            .aa {
                composes: b from './b.css';
                composes: c from './c.css';
            }
    
            .bb {
                composes: c from './c.css';
                composes: b from './b.css';
            }
        "#},
        indoc! {r#"
            :import("./c.css") {
                i__imported_c_1: c;
            }
            :import("./b.css") {
                i__imported_b_0: b;
            }
            .aa {
                composes: i__imported_b_0;
                composes: i__imported_c_1;
            }

            .bb {
                composes: i__imported_c_1;
                composes: i__imported_b_0;
            }
        "#},
        "Failed to resolve order of composed modules",
    );
}

mod topological_sort {
    use super::*;

    #[test]
    fn should_resolve_graphs() {
        let mut warnings = Vec::new();
        let graph: LinkedHashMap<&str, Vec<&str>> = LinkedHashMap::from_iter([
            ("v1", vec!["v2", "v5"]),
            ("v2", vec![]),
            ("v3", vec!["v2", "v4", "v5"]),
            ("v4", vec![]),
            ("v5", vec![]),
        ]);
        let order = topological_sort(&graph, &mut warnings);
        assert_eq!(order, vec!["v2", "v5", "v1", "v4", "v3"]);
        assert!(warnings.is_empty());
        let graph: LinkedHashMap<&str, Vec<&str>> = LinkedHashMap::from_iter([
            ("v1", vec!["v2", "v5"]),
            ("v2", vec!["v4"]),
            ("v3", vec!["v2", "v4", "v5"]),
            ("v4", vec![]),
            ("v5", vec![]),
        ]);
        let order = topological_sort(&graph, &mut warnings);
        assert_eq!(order, vec!["v4", "v2", "v5", "v1", "v3"]);
        assert!(warnings.is_empty());
    }

    #[test]
    fn cycle_in_the_graph() {
        let mut warnings = Vec::new();
        let graph: LinkedHashMap<&str, Vec<&str>> =
            LinkedHashMap::from_iter([("v1", vec!["v3"]), ("v2", vec![]), ("v3", vec!["v1"])]);
        let order = topological_sort(&graph, &mut warnings);
        assert_eq!(order, vec!["v3", "v1", "v2"]);
        assert!(!warnings.is_empty());
    }
}