use crate::text_style::Alignment;
use crate::{color_record_to_nustyle, lookup_ansi_color_style, TextStyle};
use nu_ansi_term::{Color, Style};
use nu_engine::{env::get_config, eval_block};
use nu_protocol::{
    engine::{EngineState, Stack, StateWorkingSet},
    CliError, IntoPipelineData, Value,
};
use std::collections::HashMap;

use std::fmt::{Debug, Formatter, Result};

// ComputableStyle represents the valid user style types: a single color value, or a closure which
// takes an input value and produces a color value. The latter represents a value which
// is computed at use-time.
#[derive(Debug, Clone)]
pub enum ComputableStyle {
    Static(Style),
    Closure(Value),
}

// An alias for the mapping used internally by StyleComputer.
pub type StyleMapping = HashMap<String, ComputableStyle>;
//
// A StyleComputer is an all-in-one way to compute styles. A nu command can
// simply create it with from_config(), and then use it with compute().
// It stores the engine state and stack needed to run closures that
// may be defined as a user style.
//
pub struct StyleComputer<'a> {
    engine_state: &'a EngineState,
    stack: &'a Stack,
    map: StyleMapping,
}

impl<'a> StyleComputer<'a> {
    // This is NOT meant to be used in most cases - please use from_config() instead.
    // This only exists for testing purposes.
    pub fn new(
        engine_state: &'a EngineState,
        stack: &'a Stack,
        map: StyleMapping,
    ) -> StyleComputer<'a> {
        StyleComputer {
            engine_state,
            stack,
            map,
        }
    }
    // The main method. Takes a string name which maps to a color_config style name,
    // and a Nu value to pipe into any closures that may have been defined there.
    pub fn compute(&self, style_name: &str, value: &Value) -> Style {
        match self.map.get(style_name) {
            // Static values require no computation.
            Some(ComputableStyle::Static(s)) => *s,
            // Closures are run here.
            Some(ComputableStyle::Closure(v)) => {
                let span = v.span();
                match v {
                    Value::Closure { val, .. } => {
                        let block = self.engine_state.get_block(val.block_id).clone();
                        // Because captures_to_stack() clones, we don't need to use with_env() here
                        // (contrast with_env() usage in `each` or `do`).
                        let mut stack = self.stack.captures_to_stack(val.captures.clone());

                        // Support 1-argument blocks as well as 0-argument blocks.
                        if let Some(var) = block.signature.get_positional(0) {
                            if let Some(var_id) = &var.var_id {
                                stack.add_var(*var_id, value.clone());
                            }
                        }

                        // Run the block.
                        match eval_block(
                            self.engine_state,
                            &mut stack,
                            &block,
                            value.clone().into_pipeline_data(),
                            false,
                            false,
                        ) {
                            Ok(v) => {
                                let value = v.into_value(span);
                                // These should be the same color data forms supported by color_config.
                                match value {
                                    Value::Record { .. } => color_record_to_nustyle(&value),
                                    Value::String { val, .. } => lookup_ansi_color_style(&val),
                                    _ => Style::default(),
                                }
                            }
                            // This is basically a copy of nu_cli::report_error(), but that isn't usable due to
                            // dependencies. While crudely spitting out a bunch of errors like this is not ideal,
                            // currently hook closure errors behave roughly the same.
                            Err(e) => {
                                eprintln!(
                                    "Error: {:?}",
                                    CliError(&e, &StateWorkingSet::new(self.engine_state))
                                );
                                Style::default()
                            }
                        }
                    }
                    _ => Style::default(),
                }
            }
            // There should be no other kinds of values (due to create_map() in config.rs filtering them out)
            // so this is just a fallback.
            _ => Style::default(),
        }
    }

    // Used only by the `table` command.
    pub fn style_primitive(&self, value: &Value) -> TextStyle {
        use Alignment::*;
        let s = self.compute(&value.get_type().get_non_specified_string(), value);
        match *value {
            Value::Bool { .. } => TextStyle::with_style(Left, s),
            Value::Int { .. } => TextStyle::with_style(Right, s),
            Value::Filesize { .. } => TextStyle::with_style(Right, s),
            Value::Duration { .. } => TextStyle::with_style(Right, s),
            Value::Date { .. } => TextStyle::with_style(Left, s),
            Value::Range { .. } => TextStyle::with_style(Left, s),
            Value::Float { .. } => TextStyle::with_style(Right, s),
            Value::String { .. } => TextStyle::with_style(Left, s),
            Value::Glob { .. } => TextStyle::with_style(Left, s),
            Value::Nothing { .. } => TextStyle::with_style(Left, s),
            Value::Binary { .. } => TextStyle::with_style(Left, s),
            Value::CellPath { .. } => TextStyle::with_style(Left, s),
            Value::Record { .. } | Value::List { .. } | Value::Block { .. } => {
                TextStyle::with_style(Left, s)
            }
            Value::Closure { .. }
            | Value::CustomValue { .. }
            | Value::Error { .. }
            | Value::LazyRecord { .. } => TextStyle::basic_left(),
        }
    }

    // The main constructor.
    pub fn from_config(engine_state: &'a EngineState, stack: &'a Stack) -> StyleComputer<'a> {
        let config = get_config(engine_state, stack);

        // Create the hashmap
        #[rustfmt::skip]
        let mut map: StyleMapping = [
            ("separator".to_string(), ComputableStyle::Static(Color::White.normal())),
            ("leading_trailing_space_bg".to_string(), ComputableStyle::Static(Style::default().on(Color::Rgb(128, 128, 128)))),
            ("header".to_string(), ComputableStyle::Static(Color::Green.bold())),
            ("empty".to_string(), ComputableStyle::Static(Color::Blue.normal())),
            ("bool".to_string(), ComputableStyle::Static(Color::LightCyan.normal())),
            ("int".to_string(), ComputableStyle::Static(Color::White.normal())),
            ("filesize".to_string(), ComputableStyle::Static(Color::Cyan.normal())),
            ("duration".to_string(), ComputableStyle::Static(Color::White.normal())),
            ("date".to_string(), ComputableStyle::Static(Color::Purple.normal())),
            ("range".to_string(), ComputableStyle::Static(Color::White.normal())),
            ("float".to_string(), ComputableStyle::Static(Color::White.normal())),
            ("string".to_string(), ComputableStyle::Static(Color::White.normal())),
            ("nothing".to_string(), ComputableStyle::Static(Color::White.normal())),
            ("binary".to_string(), ComputableStyle::Static(Color::White.normal())),
            ("cell-path".to_string(), ComputableStyle::Static(Color::White.normal())),
            ("row_index".to_string(), ComputableStyle::Static(Color::Green.bold())),
            ("record".to_string(), ComputableStyle::Static(Color::White.normal())),
            ("list".to_string(), ComputableStyle::Static(Color::White.normal())),
            ("block".to_string(), ComputableStyle::Static(Color::White.normal())),
            ("hints".to_string(), ComputableStyle::Static(Color::DarkGray.normal())),
            ("search_result".to_string(), ComputableStyle::Static(Color::White.normal().on(Color::Red))),
        ].into_iter().collect();

        for (key, value) in &config.color_config {
            match value {
                Value::Closure { .. } => {
                    map.insert(key.to_string(), ComputableStyle::Closure(value.clone()));
                }
                Value::Record { .. } => {
                    map.insert(
                        key.to_string(),
                        ComputableStyle::Static(color_record_to_nustyle(value)),
                    );
                }
                Value::String { val, .. } => {
                    // update the stylemap with the found key
                    let color = lookup_ansi_color_style(val.as_str());
                    if let Some(v) = map.get_mut(key) {
                        *v = ComputableStyle::Static(color);
                    } else {
                        map.insert(key.to_string(), ComputableStyle::Static(color));
                    }
                }
                // This should never occur.
                _ => (),
            }
        }
        StyleComputer::new(engine_state, stack, map)
    }
}

// Because EngineState doesn't have Debug (Dec 2022),
// this incomplete representation must be used.
impl<'a> Debug for StyleComputer<'a> {
    fn fmt(&self, f: &mut Formatter<'_>) -> Result {
        f.debug_struct("StyleComputer")
            .field("map", &self.map)
            .finish()
    }
}

#[test]
fn test_computable_style_static() {
    use nu_protocol::Span;

    let style1 = Style::default().italic();
    let style2 = Style::default().underline();
    // Create a "dummy" style_computer for this test.
    let dummy_engine_state = EngineState::new();
    let dummy_stack = Stack::new();
    let style_computer = StyleComputer::new(
        &dummy_engine_state,
        &dummy_stack,
        [
            ("string".into(), ComputableStyle::Static(style1)),
            ("row_index".into(), ComputableStyle::Static(style2)),
        ]
        .into_iter()
        .collect(),
    );
    assert_eq!(
        style_computer.compute("string", &Value::nothing(Span::unknown())),
        style1
    );
    assert_eq!(
        style_computer.compute("row_index", &Value::nothing(Span::unknown())),
        style2
    );
}

// Because each closure currently runs in a separate environment, checks that the closures have run
// must use the filesystem.
#[test]
fn test_computable_style_closure_basic() {
    use nu_test_support::{nu, nu_repl_code, playground::Playground};
    Playground::setup("computable_style_closure_basic", |dirs, _| {
        let inp = [
            r#"$env.config = {
                color_config: {
                    string: {|e| touch ($e + '.obj'); 'red' }
                }
            };"#,
            "[bell book candle] | table | ignore",
            "ls | get name | to nuon",
        ];
        let actual_repl = nu!(cwd: dirs.test(), nu_repl_code(&inp));
        assert_eq!(actual_repl.err, "");
        assert_eq!(actual_repl.out, "[bell.obj, book.obj, candle.obj]");
    });
}

#[test]
fn test_computable_style_closure_errors() {
    use nu_test_support::{nu, nu_repl_code};
    let inp = [
        r#"$env.config = {
            color_config: {
                string: {|e| $e + 2 }
            }
        };"#,
        "[bell] | table",
    ];
    let actual_repl = nu!(nu_repl_code(&inp));
    // Check that the error was printed
    assert!(actual_repl.err.contains("type mismatch for operator"));
    // Check that the value was printed
    assert!(actual_repl.out.contains("bell"));
}