use crate::build;
use crate::log::Level;
use crate::session::{ColorConfig, Session};
use std::default::Default;
use std::env;
use std::env::current_dir;
use std::error::Error;
use std::path::{Path, PathBuf};
use std::rc::Rc;

/// Configure various aspects of how LALRPOP works.
/// Intended for use within a `build.rs` script.
/// To get the default configuration, use `Configuration::new`.
#[derive(Clone, Default)]
pub struct Configuration {
    session: Session,
}

impl Configuration {
    /// Creates the default configuration; equivalent to `Configuration::default`.
    pub fn new() -> Configuration {
        Configuration::default()
    }

    /// Always use ANSI colors in output, even if output does not appear to be a TTY.
    pub fn always_use_colors(&mut self) -> &mut Configuration {
        self.session.color_config = ColorConfig::Yes;
        self
    }

    /// Never use ANSI colors in output, even if output appears to be a TTY.
    pub fn never_use_colors(&mut self) -> &mut Configuration {
        self.session.color_config = ColorConfig::No;
        self
    }

    /// Use ANSI colors in output if output appears to be a TTY, but
    /// not otherwise. This is the default.
    pub fn use_colors_if_tty(&mut self) -> &mut Configuration {
        self.session.color_config = ColorConfig::IfTty;
        self
    }

    /// Specify a custom directory to search for input files.  This
    /// directory is recursively searched for `.lalrpop` files to be
    /// considered as input files.  This configuration setting also
    /// impacts where output files are placed; paths are made relative
    /// to the input path before being resolved relative to the output
    /// path.  By default, the input directory is the current working
    /// directory.
    pub fn set_in_dir<P>(&mut self, dir: P) -> &mut Self
    where
        P: Into<PathBuf>,
    {
        self.session.in_dir = Some(dir.into());
        self
    }

    /// Specify a custom directory to use when writing output files.
    /// By default, the output directory is the same as the input
    /// directory.
    pub fn set_out_dir<P>(&mut self, dir: P) -> &mut Self
    where
        P: Into<PathBuf>,
    {
        self.session.out_dir = Some(dir.into());
        self
    }

    /// Apply `cargo` directory location conventions, by setting the
    /// input directory to `src` and the output directory to
    /// `$OUT_DIR`.
    pub fn use_cargo_dir_conventions(&mut self) -> &mut Self {
        self.set_in_dir("src")
            .set_out_dir(env::var("OUT_DIR").unwrap());
        self
    }

    /// Write output files in the same directory of the input files.
    ///
    /// If this option is enabled, you have to load the parser as a module:
    ///
    /// ```no_run
    /// mod parser; // synthesized from parser.lalrpop
    /// ```
    ///
    /// This was the default behaviour up to version 0.15.
    pub fn generate_in_source_tree(&mut self) -> &mut Self {
        self.set_in_dir(Path::new(".")).set_out_dir(Path::new("."))
    }

    /// If true, always convert `.lalrpop` files into `.rs` files, even if the
    /// `.rs` file is newer. Default is false.
    pub fn force_build(&mut self, val: bool) -> &mut Configuration {
        self.session.force_build = val;
        self
    }

    /// If true, print `rerun-if-changed` directives to standard output, so that
    /// Cargo will only rerun the build script if any of the processed
    /// `.lalrpop` files are changed. This option is independent of
    /// [`Self::force_build()`], although it would be usual to set [`Self::force_build()`] and
    /// [`Self::emit_rerun_directives()`] at the same time.
    ///
    /// While many build scripts will want to set this to `true`, the default is
    /// false, because emitting any rerun directives to Cargo will cause the
    /// script to only be rerun when Cargo thinks it is needed. This could lead
    /// to hard-to-find bugs if other parts of the build script do not emit
    /// directives correctly, or need to be rerun unconditionally.
    pub fn emit_rerun_directives(&mut self, val: bool) -> &mut Configuration {
        self.session.emit_rerun_directives = val;
        self
    }

    /// If true, emit comments into the generated code. This makes the
    /// generated code significantly larger. Default is false.
    pub fn emit_comments(&mut self, val: bool) -> &mut Configuration {
        self.session.emit_comments = val;
        self
    }

    /// If false, shrinks the generated code by removing redundant white space.
    /// Default is true.
    pub fn emit_whitespace(&mut self, val: bool) -> &mut Configuration {
        self.session.emit_whitespace = val;
        self
    }

    /// If true, emit report file about generated code.
    pub fn emit_report(&mut self, val: bool) -> &mut Configuration {
        self.session.emit_report = val;
        self
    }

    /// Minimal logs: only for errors that halt progress.
    pub fn log_quiet(&mut self) -> &mut Configuration {
        self.session.log.set_level(Level::Taciturn);
        self
    }

    /// Informative logs: give some high-level indications of
    /// progress (default).
    pub fn log_info(&mut self) -> &mut Configuration {
        self.session.log.set_level(Level::Informative);
        self
    }

    /// Verbose logs: more than info, but still not overwhelming.
    pub fn log_verbose(&mut self) -> &mut Configuration {
        self.session.log.set_level(Level::Verbose);
        self
    }

    /// Debug logs: better redirect this to a file. Intended for
    /// debugging LALRPOP itself.
    pub fn log_debug(&mut self) -> &mut Configuration {
        self.session.log.set_level(Level::Debug);
        self
    }

    /// Sets the features used during compilation, disables the use of cargo features.
    /// (Default: Loaded from `CARGO_FEATURE_{}` environment variables).
    pub fn set_features<I>(&mut self, iterable: I) -> &mut Configuration
    where
        I: IntoIterator<Item = String>,
    {
        self.session.features = Some(iterable.into_iter().collect());
        self
    }

    /// Enables "unit-testing" configuration. This is only for
    /// lalrpop-test.
    #[doc(hidden)]
    pub fn unit_test(&mut self) -> &mut Configuration {
        self.session.unit_test = true;
        self
    }

    /// Process all files according to the `set_in_dir` and
    /// `set_out_dir` configuration.
    pub fn process(&self) -> Result<(), Box<dyn Error>> {
        let root = if let Some(ref d) = self.session.in_dir {
            d.as_path()
        } else {
            Path::new(".")
        };
        self.process_dir(root)
    }

    /// Process all files in the current directory, which -- unless you
    /// have changed it -- is typically the root of the crate being compiled.
    pub fn process_current_dir(&self) -> Result<(), Box<dyn Error>> {
        self.process_dir(current_dir()?)
    }

    /// Process all `.lalrpop` files in `path`.
    pub fn process_dir<P: AsRef<Path>>(&self, path: P) -> Result<(), Box<dyn Error>> {
        let mut session = self.session.clone();

        // If in/out dir are empty, use cargo conventions by default.
        // See https://github.com/lalrpop/lalrpop/issues/280
        if session.in_dir.is_none() {
            let mut in_dir = env::current_dir()?;
            in_dir.push("src");
            session.in_dir = Some(in_dir);
        }

        if session.out_dir.is_none() {
            let out_dir = env::var_os("OUT_DIR").ok_or("missing OUT_DIR variable")?;
            session.out_dir = Some(PathBuf::from(out_dir));
        }

        if self.session.features.is_none() {
            // Pick up the features cargo sets for build scripts
            session.features = Some(
                env::vars()
                    .filter_map(|(feature_var, _)| {
                        let prefix = "CARGO_FEATURE_";
                        feature_var
                            .strip_prefix(prefix)
                            .map(|feature| feature.replace('_', "-").to_ascii_lowercase())
                    })
                    .collect(),
            );
        }

        let session = Rc::new(session);
        build::process_dir(session, path)?;
        Ok(())
    }

    /// Process the given `.lalrpop` file.
    pub fn process_file<P: AsRef<Path>>(&self, path: P) -> Result<(), Box<dyn Error>> {
        let session = Rc::new(self.session.clone());
        build::process_file(session, path)?;
        Ok(())
    }
}

/// Process all files in the current directory, which -- unless you
/// have changed it -- is typically the root of the crate being compiled.
///
/// Equivalent to `Configuration::new().process_current_dir()`.
pub fn process_root() -> Result<(), Box<dyn Error>> {
    Configuration::new().process_current_dir()
}

/// Deprecated in favor of `Configuration`.
///
/// Instead, consider using:
///
/// ```rust
/// Configuration::new().force_build(true).process_current_dir()
/// ```
///
pub fn process_root_unconditionally() -> Result<(), Box<dyn Error>> {
    Configuration::new().force_build(true).process_current_dir()
}