// Copyright 2024 FastLabs Developers

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//     http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

use std::io::Write;

use std::num::NonZeroUsize;

use std::path::PathBuf;

use std::sync::Mutex;

use std::sync::MutexGuard;

use logforth_core::Diagnostic;

use logforth_core::Error;

use logforth_core::Layout;

use logforth_core::Trap;

use logforth_core::append::Append;

use logforth_core::layout::PlainTextLayout;

use logforth_core::record::Record;

use crate::rolling::RollingFileWriter;

use crate::rolling::RollingFileWriterBuilder;

use crate::rotation::Rotation;

/// A builder to configure and create an [`File`] appender.

#[derive(Debug)]

pub struct FileBuilder {

    builder: RollingFileWriterBuilder,

    layout: Box<dyn Layout>,

}

impl FileBuilder {

    /// Create a new file appender builder.

    pub fn new(basedir: impl Into<PathBuf>, filename: impl Into<String>) -> Self {

        Self {

            builder: RollingFileWriterBuilder::new(basedir, filename),

            layout: Box::new(PlainTextLayout::default()),

        }

    }

    /// Build the [`File`] appender.

    ///

    /// # Errors

    ///

    /// Return an error if either:

    ///

    /// * The log directory cannot be created.

    /// * The configured filename is empty.

    pub fn build(self) -> Result<File, Error> {

        let FileBuilder { builder, layout } = self;

        let writer = builder.build()?;

        Ok(File::new(writer, layout))

    }

    /// Set the layout for the logs.

    ///

    /// Default to [`PlainTextLayout`].

    ///

    /// # Examples

    ///

    /// ```

    /// use logforth_append_file::FileBuilder;

    /// use logforth_layout_json::JsonLayout;

    ///

    /// let builder = FileBuilder::new("my_service", "my_app");

    /// builder.layout(JsonLayout::default());

    /// ```

    pub fn layout(mut self, layout: impl Into<Box<dyn Layout>>) -> Self {

        self.layout = layout.into();

        self

    }

    /// Set the trap for the file writer.

    ///

    /// Default to [`BestEffortTrap`].

    ///

    /// # Examples

    ///

    /// ```

    /// use logforth_append_file::FileBuilder;

    /// use logforth_core::trap::BestEffortTrap;

    ///

    /// let builder = FileBuilder::new("my_service", "my_app");

    /// builder.trap(BestEffortTrap::default());

    /// ```

    ///

    /// [`BestEffortTrap`]: logforth_core::trap::BestEffortTrap

    pub fn trap(mut self, trap: impl Into<Box<dyn Trap>>) -> Self {

        self.builder = self.builder.trap(trap);

        self

    }

    /// Set the rotation strategy to roll over log files minutely.

    pub fn rollover_minutely(mut self) -> Self {

        self.builder = self.builder.rotation(Rotation::Minutely);

        self

    }

    /// Set the rotation strategy to roll over log files hourly.

    pub fn rollover_hourly(mut self) -> Self {

        self.builder = self.builder.rotation(Rotation::Hourly);

        self

    }

    /// Set the rotation strategy to roll over log files daily at 00:00 in the local time zone.

    pub fn rollover_daily(mut self) -> Self {

        self.builder = self.builder.rotation(Rotation::Daily);

        self

    }

    /// Set the rotation strategy to roll over log files if the current log file exceeds the given

    /// size.

    ///

    /// If any time-based rotation strategy is set, the size-based rotation will be checked on the

    /// current log file after the time-based rotation check.

    pub fn rollover_size(mut self, n: NonZeroUsize) -> Self {

        self.builder = self.builder.max_file_size(n);

        self

    }

    /// Set the filename suffix.

    pub fn filename_suffix(mut self, suffix: impl Into<String>) -> Self {

        self.builder = self.builder.filename_suffix(suffix);

        self

    }

    /// Set the maximum number of log files to keep.

    pub fn max_log_files(mut self, n: NonZeroUsize) -> Self {

        self.builder = self.builder.max_log_files(n);

        self

    }

}

/// An appender that writes log records to rolling files.

#[derive(Debug)]

pub struct File {

    writer: Mutex<RollingFileWriter>,

    layout: Box<dyn Layout>,

}

impl File {

    fn new(writer: RollingFileWriter, layout: Box<dyn Layout>) -> Self {

        let writer = Mutex::new(writer);

        Self { writer, layout }

    }

    fn writer(&self) -> MutexGuard<'_, RollingFileWriter> {

        self.writer.lock().unwrap_or_else(|e| e.into_inner())

    }

}

impl Append for File {

    fn append(&self, record: &Record, diags: &[Box<dyn Diagnostic>]) -> Result<(), Error> {

        let mut bytes = self.layout.format(record, diags)?;

        bytes.push(b'\n');

        let mut writer = self.writer();

        writer.write_all(&bytes).map_err(Error::from_io_error)?;

        Ok(())

    }

    fn flush(&self) -> Result<(), Error> {

        let mut writer = self.writer();

        writer.flush().map_err(Error::from_io_error)?;

        Ok(())

    }

}

impl Drop for File {

    fn drop(&mut self) {

        let writer = self.writer.get_mut().unwrap_or_else(|e| e.into_inner());

        let _ = writer.flush();

    }

}