use crate::platform::input::legacy_input::LegacyInput;
use crate::platform::input::reedline_prompt::ReedlinePrompt;
use nu_engine::command_prelude::*;
use nu_protocol::shell_error::io::IoError;
use reedline::{FileBackedHistory, History, HistoryItem, Reedline, Signal, HISTORY_SIZE};

#[derive(Clone)]
pub struct Input;

impl LegacyInput for Input {}

impl Command for Input {
    fn name(&self) -> &str {
        "input"
    }

    fn description(&self) -> &str {
        "Get input from the user."
    }

    fn search_terms(&self) -> Vec<&str> {
        vec!["prompt", "interactive"]
    }

    fn signature(&self) -> Signature {
        Signature::build("input")
            .input_output_types(vec![
                (Type::Nothing, Type::Any), 
                (Type::List(Box::new(Type::String)), Type::Any)])
            .allow_variants_without_examples(true)
            .optional("prompt", SyntaxShape::String, "Prompt to show the user.")
            .named(
                "bytes-until-any",
                SyntaxShape::String,
                "read bytes (not text) until any of the given stop bytes is seen",
                Some('u'),
            )
            .named(
                "numchar",
                SyntaxShape::Int,
                "number of characters to read; suppresses output",
                Some('n'),
            )
            .named(
                "default",
                SyntaxShape::String,
                "default value if no input is provided",
                Some('d'),
            )
            .named(
                "history-file",
                SyntaxShape::Filepath,
                "path to a file to read/write history",
                None,
            )
            .named(
                "max-history",
                SyntaxShape::Int,
                "The maximum number of entries to keep in the history, defaults to reedline {HISTORY_SIZE}",
                None,
            )
            .switch("suppress-output", "don't print keystroke values", Some('s'))
            .category(Category::Platform)
    }

    fn run(
        &self,
        engine_state: &EngineState,
        stack: &mut Stack,
        call: &Call,
        input: PipelineData,
    ) -> Result<PipelineData, ShellError> {
        // Those options are not supported by reedline, default to the legacy
        // implementation
        let use_legacy = [
            call.get_flag::<String>(engine_state, stack, "bytes-until-any")?
                .is_some(),
            call.has_flag(engine_state, stack, "suppress-output")?,
            call.get_flag::<Spanned<i64>>(engine_state, stack, "numchar")?
                .is_some(),
        ]
        .iter()
        .any(|x| *x);

        if use_legacy {
            return self.legacy_input(engine_state, stack, call, input);
        }

        let prompt_str: Option<String> = call.opt(engine_state, stack, 0)?;
        let default_val: Option<String> = call.get_flag(engine_state, stack, "default")?;
        let history_file_val: Option<String> = call.get_flag(engine_state, stack, "history-file")?;
        let max_history: usize = call
            .get_flag::<i64>(engine_state, stack, "max-history")?
            .map(|l| if l < 0 { 0 } else { l as usize })
            .unwrap_or(HISTORY_SIZE);

        let from_io_error = IoError::factory(call.head, None);

        let default_str = match (&prompt_str, &default_val) {
            (Some(_prompt), Some(val)) => format!("(default: {val}) "),
            _ => "".to_string(),
        };

        let history_entries = match input {
            PipelineData::Value(Value::List { vals, .. }, ..) => {
                Some(vals)
            }
            _ => None,
        };

        // If we either have history entries or history file, we create an history
        let history = match (history_entries.is_some(), history_file_val.is_some()) {
            (false, false) => None,
            _ => { 
                let mut history = match history_file_val {
                    Some(file) => FileBackedHistory::with_file(max_history, file.into()),
                    None => FileBackedHistory::new(max_history)
                }.expect("Error creating history file");

                if let Some(vals) = history_entries {
                    vals.iter().for_each(|val| {
                        if let Value::String { val, .. } = val {
                            let _ = history.save(HistoryItem::from_command_line(val.clone()));
                        }
                    });
                }
                Some(history)
            },
        };

        let prompt = ReedlinePrompt {
            indicator: default_str,
            left_prompt: prompt_str.unwrap_or("".to_string()),
            right_prompt: "".to_string(),
        };

        let mut line_editor = Reedline::create();
        line_editor = line_editor.with_ansi_colors(false);
        line_editor = match history {
            Some(h) => line_editor.with_history(Box::new(h)),
            None => line_editor,
        };

        let mut buf = String::new();

        loop {
            match line_editor.read_line(&prompt) {
                Ok(Signal::Success(buffer)) => {
                    buf.push_str(&buffer);
                    break;
                }
                Ok(Signal::CtrlC) => {
                    return Err(
                        IoError::new(std::io::ErrorKind::Interrupted, call.head, None).into(),
                    );
                }
                Ok(_) => continue,
                Err(event_error) => {
                    crossterm::terminal::disable_raw_mode().map_err(&from_io_error)?;
                    return Err(from_io_error(event_error).into());
                }
            }
        }
        match default_val {
            Some(val) if buf.is_empty() => Ok(Value::string(val, call.head).into_pipeline_data()),
            _ => Ok(Value::string(buf, call.head).into_pipeline_data()),
        }
    }

    fn examples(&self) -> Vec<Example> {
        vec![
            Example {
                description: "Get input from the user, and assign to a variable",
                example: "let user_input = (input)",
                result: None,
            },
            Example {
                description: "Get two characters from the user, and assign to a variable",
                example: "let user_input = (input --numchar 2)",
                result: None,
            },
            Example {
                description: "Get input from the user with default value, and assign to a variable",
                example: "let user_input = (input --default 10)",
                result: None,
            },
            Example {
                description: "Get input from the user with history, and assign to a variable",
                example: "let user_input = ([past,command,entries] | input)",
                result: None,
            },
            Example {
                description: "Get input from the user with history backed by a file, and assign to a variable",
                example: "let user_input = (input --history-file ./history.txt)",
                result: None,
            },
        ]
    }
}

#[cfg(test)]
mod tests {
    use super::Input;

    #[test]
    fn examples_work_as_expected() {
        use crate::test_examples;
        test_examples(Input {})
    }
}