// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use errors::{Error, ErrorKind};
use rustc_serialize::json;
use std::str::FromStr;
use std::path::Path;
use runtest::ProcRes;

// These structs are a subset of the ones found in
// `syntax::json`.

#[derive(RustcEncodable, RustcDecodable)]
struct Diagnostic {
    message: String,
    code: Option<DiagnosticCode>,
    level: String,
    spans: Vec<DiagnosticSpan>,
    children: Vec<Diagnostic>,
    rendered: Option<String>,
}

#[derive(RustcEncodable, RustcDecodable, Clone)]
struct DiagnosticSpan {
    file_name: String,
    line_start: usize,
    line_end: usize,
    column_start: usize,
    column_end: usize,
    is_primary: bool,
    label: Option<String>,
    expansion: Option<Box<DiagnosticSpanMacroExpansion>>,
}

#[derive(RustcEncodable, RustcDecodable, Clone)]
struct DiagnosticSpanMacroExpansion {
    /// span where macro was applied to generate this code
    span: DiagnosticSpan,

    /// name of macro that was applied (e.g., "foo!" or "#[derive(Eq)]")
    macro_decl_name: String,
}

#[derive(RustcEncodable, RustcDecodable, Clone)]
struct DiagnosticCode {
    /// The code itself.
    code: String,
    /// An explanation for the code.
    explanation: Option<String>,
}

pub fn parse_output(file_name: &str, output: &str, proc_res: &ProcRes) -> Vec<Error> {
    output.lines()
        .flat_map(|line| parse_line(file_name, line, output, proc_res))
        .collect()
}

fn parse_line(file_name: &str, line: &str, output: &str, proc_res: &ProcRes) -> Vec<Error> {
    // The compiler sometimes intermingles non-JSON stuff into the
    // output.  This hack just skips over such lines. Yuck.
    if line.chars().next() == Some('{') {
        match json::decode::<Diagnostic>(line) {
            Ok(diagnostic) => {
                let mut expected_errors = vec![];
                push_expected_errors(&mut expected_errors, &diagnostic, &[], file_name);
                expected_errors
            }
            Err(error) => {
                proc_res.fatal(Some(&format!("failed to decode compiler output as json: \
                                              `{}`\noutput: {}\nline: {}",
                                             error,
                                             line,
                                             output)));
            }
        }
    } else {
        vec![]
    }
}

fn push_expected_errors(expected_errors: &mut Vec<Error>,
                        diagnostic: &Diagnostic,
                        default_spans: &[&DiagnosticSpan],
                        file_name: &str) {
    let spans_in_this_file: Vec<_> = diagnostic.spans
        .iter()
        .filter(|span| Path::new(&span.file_name) == Path::new(&file_name))
        .collect();

    let primary_spans: Vec<_> = spans_in_this_file.iter()
        .cloned()
        .filter(|span| span.is_primary)
        .collect();
    let primary_spans = if primary_spans.is_empty() {
        // subdiagnostics often don't have a span of their own;
        // inherit the span from the parent in that case
        default_spans
    } else {
        &primary_spans
    };

    // We break the output into multiple lines, and then append the
    // [E123] to every line in the output. This may be overkill.  The
    // intention was to match existing tests that do things like "//|
    // found `i32` [E123]" and expect to match that somewhere, and yet
    // also ensure that `//~ ERROR E123` *always* works. The
    // assumption is that these multi-line error messages are on their
    // way out anyhow.
    let with_code = |span: &DiagnosticSpan, text: &str| {
        match diagnostic.code {
            Some(ref code) =>
                // FIXME(#33000) -- it'd be better to use a dedicated
                // UI harness than to include the line/col number like
                // this, but some current tests rely on it.
                //
                // Note: Do NOT include the filename. These can easily
                // cause false matches where the expected message
                // appears in the filename, and hence the message
                // changes but the test still passes.
                format!("{}:{}: {}:{}: {} [{}]",
                        span.line_start, span.column_start,
                        span.line_end, span.column_end,
                        text, code.code.clone()),
            None =>
                // FIXME(#33000) -- it'd be better to use a dedicated UI harness
                format!("{}:{}: {}:{}: {}",
                        span.line_start, span.column_start,
                        span.line_end, span.column_end,
                        text),
        }
    };

    // Convert multi-line messages into multiple expected
    // errors. We expect to replace these with something
    // more structured shortly anyhow.
    let mut message_lines = diagnostic.message.lines();
    if let Some(first_line) = message_lines.next() {
        for span in primary_spans {
            let msg = with_code(span, first_line);
            let kind = ErrorKind::from_str(&diagnostic.level).ok();
            expected_errors.push(Error {
                line_num: span.line_start,
                kind: kind,
                msg: msg,
            });
        }
    }
    for next_line in message_lines {
        for span in primary_spans {
            expected_errors.push(Error {
                line_num: span.line_start,
                kind: None,
                msg: with_code(span, next_line),
            });
        }
    }

    // If the message has a suggestion, register that.
    if let Some(ref rendered) = diagnostic.rendered {
        let start_line = primary_spans.iter().map(|s| s.line_start).min().expect("\
            every suggestion should have at least one span");
        for (index, line) in rendered.lines().enumerate() {
            expected_errors.push(Error {
                line_num: start_line + index,
                kind: Some(ErrorKind::Suggestion),
                msg: line.to_string(),
            });
        }
    }

    // Add notes for the backtrace
    for span in primary_spans {
        for frame in &span.expansion {
            push_backtrace(expected_errors, frame, file_name);
        }
    }

    // Add notes for any labels that appear in the message.
    for span in spans_in_this_file.iter()
        .filter(|span| span.label.is_some()) {
        expected_errors.push(Error {
            line_num: span.line_start,
            kind: Some(ErrorKind::Note),
            msg: span.label.clone().unwrap(),
        });
    }

    // Flatten out the children.
    for child in &diagnostic.children {
        push_expected_errors(expected_errors, child, primary_spans, file_name);
    }
}

fn push_backtrace(expected_errors: &mut Vec<Error>,
                  expansion: &DiagnosticSpanMacroExpansion,
                  file_name: &str) {
    if Path::new(&expansion.span.file_name) == Path::new(&file_name) {
        expected_errors.push(Error {
            line_num: expansion.span.line_start,
            kind: Some(ErrorKind::Note),
            msg: format!("in this expansion of {}", expansion.macro_decl_name),
        });
    }

    for previous_expansion in &expansion.span.expansion {
        push_backtrace(expected_errors, previous_expansion, file_name);
    }
}