use core::panic;
use std::mem;

use codespan_reporting::diagnostic::Diagnostic;
use codespan_reporting::diagnostic::Label;
use codespan_reporting::files::Files;
use codespan_reporting::files::SimpleFile;
use codespan_reporting::files::SimpleFiles;
use codespan_reporting::term;
use codespan_reporting::term::termcolor::ColorChoice;
use codespan_reporting::term::termcolor::StandardStream;
use logos::Logos;
use logos::Span;

use crate::lexer::Token;

#[derive(Debug, Clone, PartialEq)]
pub struct PipelineElement {
    kind: PipelineElementKind,
    span: Span,
}

#[derive(Debug, Clone, PartialEq)]
pub enum PipelineElementKind {
    Pipe,
    Command(Vec<CommandPart>),
}

#[derive(Debug, Clone, PartialEq)]
pub struct CommandPart {
    kind: CommandPartKind,
    span: Span,
}

#[derive(Debug, Clone, PartialEq)]
pub enum CommandPartKind {
    Word(String),
    Integer(i64),
    Float(f64),
    String(String),
}

pub fn parse_syntax(input: &str) -> Vec<PipelineElement> {
    let lexer = Token::lexer(input);

    let mut r = Vec::new();

    let mut partial_command: Vec<CommandPart> = Vec::new();
    for (tok, span) in lexer.spanned().into_iter() {
        if let Ok(tok) = tok {
            match tok {
                Token::Pipe => {
                    if !partial_command.is_empty() {
                        let span = partial_command.first().unwrap().span.start
                            ..partial_command.last().unwrap().span.end;
                        r.push(PipelineElement {
                            kind: PipelineElementKind::Command(mem::replace(
                                &mut partial_command,
                                Vec::new(),
                            )),
                            span,
                        });
                    }
                    r.push(PipelineElement {
                        kind: PipelineElementKind::Pipe,
                        span,
                    });
                }
                Token::Word(word) => partial_command.push(CommandPart {
                    kind: CommandPartKind::Word(word.to_owned()),
                    span,
                }),
                Token::IntLiteral(int) => partial_command.push(CommandPart {
                    kind: CommandPartKind::Integer(int),
                    span,
                }),
                Token::FloatLiteral(float) => partial_command.push(CommandPart {
                    kind: CommandPartKind::Float(float),
                    span,
                }),
                Token::StringLiteral(string) => partial_command.push(CommandPart {
                    kind: CommandPartKind::String(string),
                    span,
                }),
                _ => {}
            }
        } else {
            panic!("Error at {span:?}")
        }
    }

    if !partial_command.is_empty() {
        let span =
            partial_command.first().unwrap().span.start..partial_command.last().unwrap().span.end;
        r.push(PipelineElement {
            kind: PipelineElementKind::Command(mem::replace(&mut partial_command, Vec::new())),
            span,
        });
    }

    r
}

pub fn check_syntax(syntax: Vec<PipelineElement>, raw_source: &str) {
    let mut files = SimpleFiles::new();
    let file_id = files.add("input", raw_source);

    if let Some(PipelineElement {
        kind: PipelineElementKind::Pipe,
        span,
    }) = syntax.first()
    {
        let err = Diagnostic::error()
            .with_message("Missing streamer for pipeline")
            .with_labels(vec![
                Label::primary(file_id, 0..span.end).with_message("expected streamer")
            ])
            .with_notes(vec!["a pipeline can't start with a pipe".to_string()]);

        let writer = StandardStream::stderr(ColorChoice::Always);
        let config = codespan_reporting::term::Config::default();

        term::emit(&mut writer.lock(), &config, &files, &err).unwrap();
    }
}

#[test]
fn test_simple_parse_pipeline() {
    let test_pipeline = "load ./image.png | invert | save ./image_processed.jpg";
    parse_syntax(test_pipeline);
}