use crate::macro_processor::error::SMPError;
use std::collections::HashMap;
use std::fs;
use std::process::Command;

// print only with debug_assertions
macro_rules! dprint {
    ($($x:tt)*) => {
        #[cfg(debug_assertions)]
        print!($($x)*)
    }
}

// Point to one or more ranges of a string, useful for highlighting parts of string
macro_rules! highlight_debug {
    ($hi_col:expr, $str:expr $(, ($pos:tt  -> $endpos:tt))*) => {
        for (i, _c) in $str.char_indices() {
            if false $(|| (i >= $pos) && (i < $endpos))* {
                dprint!("{}{}\x1b[0m", $hi_col, _c);
            } else {
                dprint!("{}", _c);
            }
        }
        dprint!("\n");
    };
    ($str:expr, $pos:expr, $endpos:expr) => {
        highlight_debug!("\x1b[7m", $str, ($pos -> $endpos))
    };
    ($str:expr, $pos:expr) => {
        highlight_debug!($str, $pos, $pos+1)
    };
}

/// Builtin for defining a new macro
fn smp_builtin_define(
    smp: &mut MacroProcessor,
    macro_name: &str,
    args: &mut [String],
) -> Result<String, SMPError> {
    if args.len() < 1 {
        return Ok(macro_name.to_string());
    }
    let arg0 = smp.process_input(&args[0])?;
    if args.len() > 1 {
        let arg1 = smp.process_input(&args[1])?;
        smp.define_macro(arg0, MacroType::String(arg1));
    } else {
        smp.define_macro(arg0, MacroType::String(String::new()));
    }
    Ok(String::new())
}

/// If macro is defined, return second argument, else return third argument if provided
fn smp_builtin_ifdef(
    smp: &mut MacroProcessor,
    macro_name: &str,
    args: &mut [String],
) -> Result<String, SMPError> {
    if args.len() < 2 {
        return Ok(macro_name.to_string());
    }
    // We need to expand the first argument here as well, but we need to make the parser
    // support literal, and phrase strings
    if smp.macros.contains_key(&args[0]) {
        return smp.process_input(&args[1]);
    }
    if args.len() > 2 {
        return smp.process_input(&args[2]);
    }
    Ok(String::new())
}

/// If macro is not defined, return second argument, else return third argument if provided
fn smp_builtin_ifndef(
    smp: &mut MacroProcessor,
    macro_name: &str,
    args: &mut [String],
) -> Result<String, SMPError> {
    if args.len() < 2 {
        return Ok(macro_name.to_string());
    }
    // We need to expand the first argument here as well, but we need to make the parser
    // support literal, and phrase strings
    if !smp.macros.contains_key(&args[0]) {
        return smp.process_input(&args[1]);
    }
    if args.len() > 2 {
        return smp.process_input(&args[2]);
    }
    Ok(String::new())
}

/// If arguments are equal, return third argument, else return fourth argument if provided
fn smp_builtin_ifeq(
    smp: &mut MacroProcessor,
    macro_name: &str,
    args: &mut [String],
) -> Result<String, SMPError> {
    if args.len() < 3 {
        return Ok(macro_name.to_string());
    }
    let arg0 = smp.process_input(&args[0])?;
    let arg1 = smp.process_input(&args[1])?;
    if arg0 == arg1 {
        return smp.process_input(&args[2]);
    }
    if args.len() > 3 {
        return smp.process_input(&args[3]);
    }
    Ok(String::new())
}

/// If arguments are not equal, return third argument, else return fourth argument if provided
fn smp_builtin_ifneq(
    smp: &mut MacroProcessor,
    macro_name: &str,
    args: &mut [String],
) -> Result<String, SMPError> {
    if args.len() < 3 {
        return Ok(macro_name.to_string());
    }
    let arg0 = smp.process_input(&args[0])?;
    let arg1 = smp.process_input(&args[1])?;
    if arg0 != arg1 {
        return smp.process_input(&args[2]);
    }
    if args.len() > 3 {
        return smp.process_input(&args[3]);
    }
    return Ok(String::new());
}

/// Include a new file, and process it normally. There is no loop protection here!
fn smp_builtin_include(
    smp: &mut MacroProcessor,
    macro_name: &str,
    args: &mut [String],
) -> Result<String, SMPError> {
    if args.len() < 1 {
        return Ok(macro_name.to_string());
    }
    let arg0 = smp.process_input(&args[0])?;
    let input_file = fs::read_to_string(&arg0).map_err(|e| SMPError::IncludeError(2, e, arg0))?;
    return smp.process_input(&input_file);
}

/// Include a new file verbatum, don't do ANY additional processing
fn smp_builtin_include_verbatum(
    smp: &mut MacroProcessor,
    macro_name: &str,
    args: &mut [String],
) -> Result<String, SMPError> {
    if args.len() < 1 {
        return Ok(macro_name.to_string());
    }
    let arg0 = smp.process_input(&args[0])?;
    fs::read_to_string(&arg0).map_err(|e| SMPError::IncludeError(2, e, arg0))
}

/// Simply execute argument as shell command
fn smp_builtin_shell(
    smp: &mut MacroProcessor,
    macro_name: &str,
    args: &mut [String],
) -> Result<String, SMPError> {
    if args.len() < 1 {
        return Ok(macro_name.to_string());
    }
    let arg0 = smp.process_input(&args[0])?;
    let res = Command::new("sh").arg("-c").arg(arg0).output();
    match res {
        Ok(output) => String::from_utf8(output.stdout)
            .map_err(|e| SMPError::ShellCommandError(1, Box::new(e))),
        Err(_) => Ok(String::new()),
    }
}

/// Would like one that is better than this tbh
fn smp_builtin_expr(
    smp: &mut MacroProcessor,
    macro_name: &str,
    args: &mut [String],
) -> Result<String, SMPError> {
    if args.len() < 1 {
        return Ok(macro_name.to_string());
    }

    for arg in args.iter_mut() {
        *arg = smp.process_input(&arg)?;
    }

    let res = Command::new("expr").args(args).output();
    match res {
        Ok(output) => String::from_utf8(output.stdout)
            .map_err(|e| SMPError::ShellCommandError(1, Box::new(e))),
        Err(_) => Ok(String::new()),
    }
}

/// Indent argument 2 by N spaces
fn smp_builtin_indent(
    smp: &mut MacroProcessor,
    _macro_name: &str,
    args: &mut [String],
) -> Result<String, SMPError> {
    let indent_size = args[0].parse::<u32>().unwrap_or(0);
    let mut out = String::with_capacity(args[1].len());
    for l in args[1].lines() {
        let mut lin = String::with_capacity(indent_size.try_into().unwrap_or(0) + l.len());
        if args.len() <= 2 || (args[2] != "skip_first") {
            for _ in 0..indent_size {
                lin.push(' ');
            }
        }
        lin.push_str(&smp.process_input(&l)?);
        out.push_str(&lin);
    }
    Ok(String::new())
}

/// Types of macros, this is to make it easy to store both functions and strings
#[derive(Clone)]
pub enum MacroType {
    /// When expanded, the associated function will be expanded
    Function(
        fn(
            smp: &mut MacroProcessor,
            macro_name: &str,
            args: &mut [String],
        ) -> Result<String, SMPError>,
    ),
    /// Will be expanded in-place to the String
    String(String),
}

/// Possible parser states
#[derive(Debug, PartialEq)]
enum ParserState {
    Normal,
    InMacro,
    InMacroArgs,
    DNL,
}

/// Defines a MacroProcessor object, with it's associated state
/// the state mostly includes the defined macros
#[derive(Clone)]
pub struct MacroProcessor {
    /// All currently defined macros in this MacroProcessor
    pub macros: HashMap<String, MacroType>,
}

impl MacroProcessor {
    pub fn new() -> Self {
        let mut smp = Self {
            macros: HashMap::new(),
        };
        smp.define_builtins();
        smp
    }

    /// Bootstrapping-function for defining all builtins,
    /// the same way all other macros might be defined
    fn define_builtins(&mut self) {
        self.define_macro(
            String::from("define"),
            MacroType::Function(smp_builtin_define),
        );
        self.define_macro(
            String::from("ifdef"),
            MacroType::Function(smp_builtin_ifdef),
        );
        self.define_macro(
            String::from("ifndef"),
            MacroType::Function(smp_builtin_ifndef),
        );
        self.define_macro(String::from("ifeq"), MacroType::Function(smp_builtin_ifeq));
        self.define_macro(
            String::from("ifneq"),
            MacroType::Function(smp_builtin_ifneq),
        );
        self.define_macro(
            String::from("include"),
            MacroType::Function(smp_builtin_include),
        );
        self.define_macro(
            String::from("include_verbatum"),
            MacroType::Function(smp_builtin_include_verbatum),
        );
        self.define_macro(
            String::from("shell"),
            MacroType::Function(smp_builtin_shell),
        );
        self.define_macro(
            String::from("indent"),
            MacroType::Function(smp_builtin_indent),
        );
        self.define_macro(String::from("expr"), MacroType::Function(smp_builtin_expr));
        // format('Result id %d', 3282)
    }

    /// Define a new macro as a string that will be expanded in-place
    ///
    /// # Arguments
    ///
    /// * `name` - The name of the new macro
    /// * `body` - The body of the new macro, this will be expanded when macro is executed
    pub fn define_macro_string(&mut self, name: String, body: String) {
        self.macros.insert(name, MacroType::String(body));
    }

    /// Define a new macro as any MacroType
    ///
    /// # Arguments
    ///
    /// * `name` - The name of the new macro
    /// * `macro_expansion` - The MacroType struct to use.
    pub fn define_macro(&mut self, name: String, macro_expansion: MacroType) {
        self.macros.insert(name, macro_expansion);
    }

    /// This expands a macro definition, and it executes builtin functions, like define
    ///
    /// # Arguments
    ///
    /// * `macro_name` - Name of macro to expand if it exists
    /// * `args` - List of arguments parsed along with macro invokation (empty list if no arguments were parsed)
    fn expand_macro(&mut self, macro_name: &str, args: &mut [String]) -> Result<String, SMPError> {
        let Some(macro_body) = self.macros.get(macro_name) else {
            return Ok(format!("{}", macro_name));
        };

        match macro_body {
            MacroType::String(body) => {
                let mut expanded = body.clone();
                // The expanded macro, should _probably_ be expanded again
                // The below is a okay _idea_, but I am not sure if I want to have this syntax for
                // functions defined in normal smp code
                for (i, arg) in args.iter().enumerate() {
                    let placeholder = format!("${}", i + 1);
                    expanded = expanded.replace(&placeholder, arg);
                }
                self.process_input(&expanded)
            }
            MacroType::Function(func) => {
                return func(self, macro_name, args);
            }
            MacroType::Array(vec) => return Ok(format!("Array[{}]", vec.len())),
        }
    }

    /// Do macro processing of a input string
    ///
    /// This is the main function used for processing a input string,
    /// will return the processed string.
    /// Will be called recursively if needed.
    /// Subsequent calls will keep the state from the previous call.
    /// This includes macro definitions.
    ///
    /// # Arguments
    ///
    /// * `input` - The text to process
    pub fn process_input(&mut self, input: &str) -> Result<String, SMPError> {
        let mut output = String::new();
        let mut state = ParserState::Normal;
        let mut macro_name = String::new();
        let mut macro_args = Vec::new();
        let mut argument = String::new();
        let mut macro_name_start = 0;

        let mut skip_next_line_ending = false;

        let mut in_quote_single = false;
        let mut in_quote_double = false;

        let mut parens_level = 0;

        for (i, c) in input.char_indices() {
            highlight_debug!(input, macro_name_start, i);

            match state {
                ParserState::DNL => {
                    if c == '\n' {
                        state = ParserState::Normal;
                    }
                }
                ParserState::Normal => {
                    macro_name_start = i;

                    if skip_next_line_ending && (c == '\n') {
                        skip_next_line_ending = false;
                        continue;
                    }

                    if c.is_alphanumeric() {
                        state = ParserState::InMacro;
                        macro_name.push(c);
                    } else {
                        output.push(c);
                    }
                }
                ParserState::InMacro => {
                    if c.is_alphanumeric() || c == '_' {
                        macro_name.push(c);
                    } else if c == '(' {
                        parens_level += 1;
                        state = ParserState::InMacroArgs;
                    } else {
                        if self.macros.contains_key(&macro_name) {
                            highlight_debug!("\x1b[32m\x1b[7m", input, (macro_name_start -> i));
                        }
                        if macro_name == "SNNL" {
                            skip_next_line_ending = c != '\n';
                        } else if macro_name == "DNL" {
                            if c != '\n' {
                                state = ParserState::DNL;
                            }
                            macro_name.clear();
                            continue;
                        } else {
                            let expanded = self.expand_macro(&macro_name, &mut [])?;
                            output.push_str(&expanded);
                            output.push(c);
                        }
                        macro_name.clear();
                        state = ParserState::Normal;
                    }
                }
                ParserState::InMacroArgs => {
                    if (c == ')') && (parens_level == 1) {
                        highlight_debug!("\x1b[32m\x1b[7m", input, (macro_name_start -> i));
                        parens_level = 0;
                        macro_args.push(argument.trim().to_string());
                        let expanded = self.expand_macro(&macro_name, &mut macro_args)?;
                        output.push_str(&expanded);
                        state = ParserState::Normal;
                        macro_name.clear();
                        macro_args.clear();
                        argument.clear();
                    } else if (c == ',') && (parens_level == 1) {
                        macro_args.push(argument.trim().to_string());
                        argument.clear();
                    } else {
                        if c == '(' {
                            parens_level += 1;
                        }
                        if c == ')' {
                            parens_level -= 1;
                        }
                        argument.push(c);
                    }
                }
            }
        }

        // Handle cases where the text ends with a macro without arguments
        if !macro_name.is_empty() {
            output.push_str(&self.expand_macro(&macro_name, &mut [])?);
        }

        Ok(output)
    }
}