use std::{borrow::Cow, io, io::prelude::Write};

use super::OutputFormatter;
use crate::{
    console::{ConsoleTestState, OutputLocation},
    test_result::TestResult,
    time,
    types::TestDesc,
};

pub(crate) struct JsonFormatter<T> {
    out: OutputLocation<T>,
}

impl<T: Write> JsonFormatter<T> {
    pub fn new(out: OutputLocation<T>) -> Self {
        Self { out }
    }

    fn writeln_message(&mut self, s: &str) -> io::Result<()> {
        assert!(!s.contains('\n'));

        self.out.write_all(s.as_ref())?;
        self.out.write_all(b"\n")
    }

    fn write_message(&mut self, s: &str) -> io::Result<()> {
        assert!(!s.contains('\n'));

        self.out.write_all(s.as_ref())
    }

    fn write_event(
        &mut self,
        ty: &str,
        name: &str,
        evt: &str,
        exec_time: Option<&time::TestExecTime>,
        stdout: Option<Cow<'_, str>>,
        extra: Option<&str>,
    ) -> io::Result<()> {
        // A doc test's name includes a filename which must be escaped for correct json.
        self.write_message(&*format!(
            r#"{{ "type": "{}", "name": "{}", "event": "{}""#,
            ty,
            EscapedString(name),
            evt
        ))?;
        if let Some(exec_time) = exec_time {
            self.write_message(&*format!(r#", "exec_time": {}"#, exec_time.0.as_secs_f64()))?;
        }
        if let Some(stdout) = stdout {
            self.write_message(&*format!(r#", "stdout": "{}""#, EscapedString(stdout)))?;
        }
        if let Some(extra) = extra {
            self.write_message(&*format!(r#", {}"#, extra))?;
        }
        self.writeln_message(" }")
    }
}

impl<T: Write> OutputFormatter for JsonFormatter<T> {
    fn write_run_start(&mut self, test_count: usize, shuffle_seed: Option<u64>) -> io::Result<()> {
        let shuffle_seed_json = if let Some(shuffle_seed) = shuffle_seed {
            format!(r#", "shuffle_seed": {}"#, shuffle_seed)
        } else {
            String::new()
        };
        self.writeln_message(&*format!(
            r#"{{ "type": "suite", "event": "started", "test_count": {}{} }}"#,
            test_count, shuffle_seed_json
        ))
    }

    fn write_test_start(&mut self, desc: &TestDesc) -> io::Result<()> {
        self.writeln_message(&*format!(
            r#"{{ "type": "test", "event": "started", "name": "{}" }}"#,
            EscapedString(desc.name.as_slice())
        ))
    }

    fn write_result(
        &mut self,
        desc: &TestDesc,
        result: &TestResult,
        exec_time: Option<&time::TestExecTime>,
        stdout: &[u8],
        state: &ConsoleTestState,
    ) -> io::Result<()> {
        let display_stdout = state.options.display_output || *result != TestResult::TrOk;
        let stdout = if display_stdout && !stdout.is_empty() {
            Some(String::from_utf8_lossy(stdout))
        } else {
            None
        };
        match *result {
            TestResult::TrOk => {
                self.write_event("test", desc.name.as_slice(), "ok", exec_time, stdout, None)
            }

            TestResult::TrFailed => {
                self.write_event("test", desc.name.as_slice(), "failed", exec_time, stdout, None)
            }

            TestResult::TrTimedFail => self.write_event(
                "test",
                desc.name.as_slice(),
                "failed",
                exec_time,
                stdout,
                Some(r#""reason": "time limit exceeded""#),
            ),

            TestResult::TrFailedMsg(ref m) => self.write_event(
                "test",
                desc.name.as_slice(),
                "failed",
                exec_time,
                stdout,
                Some(&*format!(r#""message": "{}""#, EscapedString(m))),
            ),

            TestResult::TrIgnored => self.write_event(
                "test",
                desc.name.as_slice(),
                "ignored",
                exec_time,
                stdout,
                desc.ignore_message
                    .map(|msg| format!(r#""message": "{}""#, EscapedString(msg)))
                    .as_deref(),
            ),

            TestResult::TrBench(ref bs) => {
                let median = bs.ns_iter_summ.median as usize;
                let deviation = (bs.ns_iter_summ.max - bs.ns_iter_summ.min) as usize;

                let mbps = if bs.mb_s == 0 {
                    String::new()
                } else {
                    format!(r#", "mib_per_second": {}"#, bs.mb_s)
                };

                let line = format!(
                    "{{ \"type\": \"bench\", \
                     \"name\": \"{}\", \
                     \"median\": {}, \
                     \"deviation\": {}{} }}",
                    EscapedString(desc.name.as_slice()),
                    median,
                    deviation,
                    mbps
                );

                self.writeln_message(&*line)
            }
        }
    }

    fn write_timeout(&mut self, desc: &TestDesc) -> io::Result<()> {
        self.writeln_message(&*format!(
            r#"{{ "type": "test", "event": "timeout", "name": "{}" }}"#,
            EscapedString(desc.name.as_slice())
        ))
    }

    fn write_run_finish(&mut self, state: &ConsoleTestState) -> io::Result<bool> {
        self.write_message(&*format!(
            "{{ \"type\": \"suite\", \
             \"event\": \"{}\", \
             \"passed\": {}, \
             \"failed\": {}, \
             \"ignored\": {}, \
             \"measured\": {}, \
             \"filtered_out\": {}",
            if state.failed == 0 { "ok" } else { "failed" },
            state.passed,
            state.failed,
            state.ignored,
            state.measured,
            state.filtered_out,
        ))?;

        if let Some(ref exec_time) = state.exec_time {
            let time_str = format!(", \"exec_time\": {}", exec_time.0.as_secs_f64());
            self.write_message(&time_str)?;
        }

        self.writeln_message(" }")?;

        Ok(state.failed == 0)
    }
}

/// A formatting utility used to print strings with characters in need of escaping.
/// Base code taken form `libserialize::json::escape_str`
struct EscapedString<S: AsRef<str>>(S);

impl<S: AsRef<str>> std::fmt::Display for EscapedString<S> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> ::std::fmt::Result {
        let mut start = 0;

        for (i, byte) in self.0.as_ref().bytes().enumerate() {
            let escaped = match byte {
                b'"' => "\\\"",
                b'\\' => "\\\\",
                b'\x00' => "\\u0000",
                b'\x01' => "\\u0001",
                b'\x02' => "\\u0002",
                b'\x03' => "\\u0003",
                b'\x04' => "\\u0004",
                b'\x05' => "\\u0005",
                b'\x06' => "\\u0006",
                b'\x07' => "\\u0007",
                b'\x08' => "\\b",
                b'\t' => "\\t",
                b'\n' => "\\n",
                b'\x0b' => "\\u000b",
                b'\x0c' => "\\f",
                b'\r' => "\\r",
                b'\x0e' => "\\u000e",
                b'\x0f' => "\\u000f",
                b'\x10' => "\\u0010",
                b'\x11' => "\\u0011",
                b'\x12' => "\\u0012",
                b'\x13' => "\\u0013",
                b'\x14' => "\\u0014",
                b'\x15' => "\\u0015",
                b'\x16' => "\\u0016",
                b'\x17' => "\\u0017",
                b'\x18' => "\\u0018",
                b'\x19' => "\\u0019",
                b'\x1a' => "\\u001a",
                b'\x1b' => "\\u001b",
                b'\x1c' => "\\u001c",
                b'\x1d' => "\\u001d",
                b'\x1e' => "\\u001e",
                b'\x1f' => "\\u001f",
                b'\x7f' => "\\u007f",
                _ => {
                    continue;
                }
            };

            if start < i {
                f.write_str(&self.0.as_ref()[start..i])?;
            }

            f.write_str(escaped)?;

            start = i + 1;
        }

        if start != self.0.as_ref().len() {
            f.write_str(&self.0.as_ref()[start..])?;
        }

        Ok(())
    }
}