# This file is a part of Julia. License is MIT: https://julialang.org/license

using Logging: Logging, AbstractLogger, LogLevel, Info, with_logger
import Base: occursin

#-------------------------------------------------------------------------------
"""
    LogRecord

Stores the results of a single log event. Fields:

* `level`: the [`LogLevel`](@ref) of the log message
* `message`: the textual content of the log message
* `_module`: the module of the log event
* `group`: the logging group (by default, the name of the file containing the log event)
* `id`: the ID of the log event
* `file`: the file containing the log event
* `line`: the line within the file of the log event
* `kwargs`: any keyword arguments passed to the log event
"""
struct LogRecord
    level
    message
    _module
    group
    id
    file
    line
    kwargs
end
LogRecord(args...; kwargs...) = LogRecord(args..., kwargs)

struct Ignored ; end

#-------------------------------------------------------------------------------
# Logger with extra test-related state
mutable struct TestLogger <: AbstractLogger
    logs::Vector{LogRecord}
    min_level::LogLevel
    catch_exceptions::Bool
    shouldlog_args
    message_limits::Dict{Any,Int}
    respect_maxlog::Bool
end

"""
    TestLogger(; min_level=Info, catch_exceptions=false)

Create a `TestLogger` which captures logged messages in its `logs::Vector{LogRecord}` field.

Set `min_level` to control the `LogLevel`, `catch_exceptions` for whether or not exceptions
thrown as part of log event generation should be caught, and `respect_maxlog` for whether
or not to follow the convention of logging messages with `maxlog=n` for some integer `n` at
most `n` times.

See also: [`LogRecord`](@ref).

## Example

```jldoctest
julia> using Test, Logging

julia> f() = @info "Hi" number=5;

julia> test_logger = TestLogger();

julia> with_logger(test_logger) do
           f()
           @info "Bye!"
       end

julia> @test test_logger.logs[1].message == "Hi"
Test Passed

julia> @test test_logger.logs[1].kwargs[:number] == 5
Test Passed

julia> @test test_logger.logs[2].message == "Bye!"
Test Passed
```
"""
TestLogger(; min_level=Info, catch_exceptions=false, respect_maxlog=true) =
    TestLogger(LogRecord[], min_level, catch_exceptions, nothing, Dict{Any, Int}(), respect_maxlog)
Logging.min_enabled_level(logger::TestLogger) = logger.min_level

function Logging.shouldlog(logger::TestLogger, level, _module, group, id)
    if get(logger.message_limits, id, 1) > 0
        logger.shouldlog_args = (level, _module, group, id)
        true
    else
        false
    end
end

function Logging.handle_message(logger::TestLogger, level, msg, _module,
                                group, id, file, line; kwargs...)
    @nospecialize
    if logger.respect_maxlog
        maxlog = get(kwargs, :maxlog, nothing)
        if maxlog isa Core.BuiltinInts
            remaining = get!(logger.message_limits, id, Int(maxlog)::Int)
            logger.message_limits[id] = remaining - 1
            remaining > 0 || return
        end
    end
    push!(logger.logs, LogRecord(level, msg, _module, group, id, file, line, kwargs))
end

# Catch exceptions for the test logger only if specified
Logging.catch_exceptions(logger::TestLogger) = logger.catch_exceptions

function collect_test_logs(f; kwargs...)
    logger = TestLogger(; kwargs...)
    value = with_logger(f, logger)
    logger.logs, value
end


#-------------------------------------------------------------------------------
# Log testing tools

# Failure result type for log testing
struct LogTestFailure <: Result
    orig_expr
    source::LineNumberNode
    patterns
    logs
end
function Base.show(io::IO, t::LogTestFailure)
    printstyled(io, "Log Test Failed"; bold=true, color=Base.error_color())
    print(io, " at ")
    printstyled(io, something(t.source.file, :none), ":", t.source.line, "\n"; bold=true, color=:default)
    println(io, "  Expression: ", t.orig_expr)
    println(io, "  Log Pattern: ", join(t.patterns, " "))
    println(io, "  Captured Logs: ")
    for l in t.logs
        println(io, "    ", l)
    end
end

# Patch support for LogTestFailure into Base.Test test set types
# TODO: Would be better if `Test` itself allowed us to handle this more neatly.
function record(::FallbackTestSet, t::LogTestFailure)
    println(t)
    throw(FallbackTestSetException("There was an error during testing"))
end

function record(ts::DefaultTestSet, t::LogTestFailure)
    if TESTSET_PRINT_ENABLE[]
        printstyled(ts.description, ": ", color=:white)
        print(t)
        Base.show_backtrace(stdout, scrub_backtrace(backtrace()))
        println()
    end
    # Hack: convert to `Fail` so that test summarization works correctly
    push!(ts.results, Fail(:test, t.orig_expr, t.logs, nothing, nothing, t.source, false))
    return t
end

"""
    @test_logs [log_patterns...] [keywords] expression

Collect a list of log records generated by `expression` using
`collect_test_logs`, check that they match the sequence `log_patterns`, and
return the value of `expression`.  The `keywords` provide some simple filtering
of log records: the `min_level` keyword controls the minimum log level which
will be collected for the test, the `match_mode` keyword defines how matching
will be performed (the default `:all` checks that all logs and patterns match
pairwise; use `:any` to check that the pattern matches at least once somewhere
in the sequence.)

The most useful log pattern is a simple tuple of the form `(level,message)`.
A different number of tuple elements may be used to match other log metadata,
corresponding to the arguments to passed to `AbstractLogger` via the
`handle_message` function: `(level,message,module,group,id,file,line)`.
Elements which are present will be matched pairwise with the log record fields
using `==` by default, with the special cases that `Symbol`s may be used for
the standard log levels, and `Regex`s in the pattern will match string or
Symbol fields using `occursin`.

# Examples

Consider a function which logs a warning, and several debug messages:

    function foo(n)
        @info "Doing foo with n=\$n"
        for i=1:n
            @debug "Iteration \$i"
        end
        42
    end

We can test the info message using

    @test_logs (:info,"Doing foo with n=2") foo(2)

If we also wanted to test the debug messages, these need to be enabled with the
`min_level` keyword:

    using Logging
    @test_logs (:info,"Doing foo with n=2") (:debug,"Iteration 1") (:debug,"Iteration 2") min_level=Logging.Debug foo(2)

If you want to test that some particular messages are generated while ignoring the rest,
you can set the keyword `match_mode=:any`:

    using Logging
    @test_logs (:info,) (:debug,"Iteration 42") min_level=Logging.Debug match_mode=:any foo(100)

The macro may be chained with `@test` to also test the returned value:

    @test (@test_logs (:info,"Doing foo with n=2") foo(2)) == 42

If you want to test for the absence of warnings, you can omit specifying log
patterns and set the `min_level` accordingly:

    # test that the expression logs no messages when the logger level is warn:
    @test_logs min_level=Logging.Warn @info("Some information") # passes
    @test_logs min_level=Logging.Warn @warn("Some information") # fails

If you want to test the absence of warnings (or error messages) in
[`stderr`](@ref) which are not generated by `@warn`, see [`@test_nowarn`](@ref).
"""
macro test_logs(exs...)
    length(exs) >= 1 || throw(ArgumentError("""`@test_logs` needs at least one arguments.
                               Usage: `@test_logs [msgs...] expr_to_run`"""))
    patterns = Any[]
    kwargs = Any[]
    for e in exs[1:end-1]
        if e isa Expr && e.head === :(=)
            push!(kwargs, esc(Expr(:kw, e.args...)))
        else
            push!(patterns, esc(e))
        end
    end
    expression = exs[end]
    orig_expr = QuoteNode(expression)
    sourceloc = QuoteNode(__source__)
    Base.remove_linenums!(quote
        let testres=nothing, value=nothing
            try
                didmatch,logs,value = match_logs($(patterns...); $(kwargs...)) do
                    $(esc(expression))
                end
                if didmatch
                    testres = Pass(:test, $orig_expr, nothing, value, $sourceloc)
                else
                    testres = LogTestFailure($orig_expr, $sourceloc,
                                             $(QuoteNode(exs[1:end-1])), logs)
                end
            catch e
                testres = Error(:test_error, $orig_expr, e, Base.current_exceptions(), $sourceloc)
            end
            Test.record(Test.get_testset(), testres)
            value
        end
    end)
end

function match_logs(f, patterns...; match_mode::Symbol=:all, kwargs...)
    logs,value = collect_test_logs(f; kwargs...)
    if match_mode === :all
        didmatch = length(logs) == length(patterns) &&
            all(occursin(p, l) for (p,l) in zip(patterns, logs))
    elseif match_mode === :any
        didmatch = all(any(occursin(p, l) for l in logs) for p in patterns)
    end
    didmatch,logs,value
end

# TODO: Use a version of parse_level from stdlib/Logging, when it exists.
function parse_level(level::Symbol)
    if      level === :belowminlevel  return  Logging.BelowMinLevel
    elseif  level === :debug          return  Logging.Debug
    elseif  level === :info           return  Logging.Info
    elseif  level === :warn           return  Logging.Warn
    elseif  level === :error          return  Logging.Error
    elseif  level === :abovemaxlevel  return  Logging.AboveMaxLevel
    else
        throw(ArgumentError("Unknown log level $level"))
    end
end

logfield_contains(a, b) = a == b
logfield_contains(a, r::Regex) = occursin(r, a)
logfield_contains(a::Symbol, r::Regex) = occursin(r, String(a))
logfield_contains(a::LogLevel, b::Symbol) = a == parse_level(b)
logfield_contains(a, b::Ignored) = true

function occursin(pattern::Tuple, r::LogRecord)
    stdfields = (r.level, r.message, r._module, r.group, r.id, r.file, r.line)
    all(logfield_contains(f, p) for (f, p) in zip(stdfields[1:length(pattern)], pattern))
end

"""
    @test_deprecated [pattern] expression

When `--depwarn=yes`, test that `expression` emits a deprecation warning and
return the value of `expression`.  The log message string will be matched
against `pattern` which defaults to `r"deprecated"i`.

When `--depwarn=no`, simply return the result of executing `expression`.  When
`--depwarn=error`, check that an ErrorException is thrown.

# Examples

```
# Deprecated in julia 0.7
@test_deprecated num2hex(1)

# The returned value can be tested by chaining with @test:
@test (@test_deprecated num2hex(1)) == "0000000000000001"
```
"""
macro test_deprecated(exs...)
    1 <= length(exs) <= 2 || throw(ArgumentError("""`@test_deprecated` expects one or two arguments.
                               Usage: `@test_deprecated [pattern] expr_to_run`"""))
    pattern = length(exs) == 1 ? r"deprecated"i : esc(exs[1])
    expression = esc(exs[end])
    res = quote
        dw = Base.JLOptions().depwarn
        if dw == 2
            # TODO: Remove --depwarn=error if possible and replace with a more
            # flexible mechanism so we don't have to do this.
            @test_throws ErrorException $expression
        elseif dw == 1
            @test_logs (:warn, $pattern, Ignored(), :depwarn) match_mode=:any $expression
        else
            $expression
        end
    end
    # Propagate source code location of @test_logs to @test macro
    # FIXME: Use rewrite_sourceloc!() for this - see #22623
    res.args[4].args[2].args[2].args[2] = __source__
    res.args[4].args[3].args[2].args[2].args[2] = __source__
    res
end
