/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil; -*- */
// SPDX-License-Identifier: MIT OR LGPL-2.0-or-later
// SPDX-FileCopyrightText: 2014 Endless Mobile, Inc.
// SPDX-FileContributor: Authored By: Sam Spilsbury <sam@endlessm.com>

#include <config.h>

#include <stdint.h>
#include <string.h>  // for strcmp, strlen

#include <new>

#include <gio/gio.h>
#include <glib-object.h>

#include <js/GCAPI.h>  // for JS_AddExtraGCRootsTracer, JS_Remove...
#include <js/PropertyAndElement.h>
#include <js/Realm.h>
#include <js/RootingAPI.h>
#include <js/TracingAPI.h>
#include <js/TypeDecls.h>
#include <js/Utility.h>  // for UniqueChars
#include <js/Value.h>
#include <js/experimental/CodeCoverage.h>  // for EnableCodeCoverage
#include <jsapi.h>                         // for JS_WrapObject
#include <mozilla/Result.h>
#include <mozilla/Try.h>

#include "gjs/atoms.h"
#include "gjs/auto.h"
#include "gjs/context-private.h"
#include "gjs/context.h"
#include "gjs/coverage.h"
#include "gjs/gerror-result.h"
#include "gjs/global.h"
#include "gjs/jsapi-util.h"
#include "gjs/macros.h"

using Gjs::GErrorResult;
using mozilla::Err, mozilla::Ok;

static bool s_coverage_enabled = false;

struct _GjsCoverage {
    GObject parent;
};

struct GjsCoveragePrivate {
    char** prefixes;
    GjsContext* coverage_context;
    JS::Heap<JSObject*> global;

    GFile* output_dir;
};

G_DEFINE_TYPE_WITH_PRIVATE(GjsCoverage,
                           gjs_coverage,
                           G_TYPE_OBJECT)

enum GjsCoverageProps : uint8_t {
    PROP_PREFIXES = 1,
    PROP_CONTEXT,
    PROP_CACHE,
    PROP_OUTPUT_DIRECTORY,
};
static GParamSpec* gjs_coverage_props[PROP_OUTPUT_DIRECTORY + 1];

[[nodiscard]]
static char* get_file_identifier(GFile* source_file) {
    char* path = g_file_get_path(source_file);
    if (!path)
        path = g_file_get_uri(source_file);
    return path;
}

[[nodiscard]]
static GErrorResult<> write_source_file_header(GOutputStream* stream,
                                               GFile* source_file) {
    Gjs::AutoChar path{get_file_identifier(source_file)};
    Gjs::AutoError error;
    if (!g_output_stream_printf(stream, nullptr, nullptr, error.out(),
                                "SF:%s\n", path.get()))
        return Err(error.release());
    return Ok{};
}

[[nodiscard]]
static GErrorResult<> copy_source_file_to_coverage_output(
    GFile* source_file, GFile* destination_file) {
    /* We need to recursively make the directory we want to copy to, as
     * g_file_copy doesn't do that */
    Gjs::AutoError error;
    Gjs::AutoUnref<GFile> destination_dir{g_file_get_parent(destination_file)};
    if (!g_file_make_directory_with_parents(destination_dir, nullptr,
                                            error.out())) {
        if (!g_error_matches(error, G_IO_ERROR, G_IO_ERROR_EXISTS))
            return Err(error.release());
        error.reset();
    }

    if (!g_file_copy(source_file, destination_file, G_FILE_COPY_OVERWRITE,
                     nullptr, nullptr, nullptr, error.out()))
        return Err(error.release());
    return Ok{};
}

// This function will strip a URI scheme and return the string with the URI
// scheme stripped or nullptr if the path was not a valid URI
[[nodiscard]]
static char* strip_uri_scheme(const char* potential_uri) {
    char* uri_header = g_uri_parse_scheme(potential_uri);

    if (uri_header) {
        size_t offset = strlen(uri_header);
        g_free(uri_header);

        /* g_uri_parse_scheme() only parses the name of the scheme, we also need
         * to strip the characters ':///' */
        return g_strdup(potential_uri + offset + 4);
    }

    return nullptr;
}

/* This function will return a string of pathname components from the first
 * directory indicating where two directories diverge. For instance:
 *
 * child: /a/b/c/d/e
 * parent: /a/b/d/
 *
 * Will return: c/d/e
 *
 * If the directories are not at all similar then the full dirname of the
 * child_path effectively be returned.
 *
 * As a special case, child paths that are a URI automatically return the full
 * URI path with the URI scheme and leading slash stripped out.
 */
[[nodiscard]]
static char* find_diverging_child_components(GFile* child, GFile* parent) {
    Gjs::AutoUnref<GFile> ancestor{parent, Gjs::TakeOwnership{}};
    while (ancestor) {
        char* relpath = g_file_get_relative_path(ancestor, child);
        if (relpath)
            return relpath;

        ancestor = g_file_get_parent(ancestor);
    }

    /* This is a special case of getting the URI below. The difference is that
     * this gives you a regular path name; getting it through the URI would give
     * a URI-encoded path (%20 for spaces, etc.) */
    Gjs::AutoUnref<GFile> root{g_file_new_for_path("/")};
    char* child_path = g_file_get_relative_path(root, child);
    if (child_path)
        return child_path;

    Gjs::AutoChar child_uri{g_file_get_uri(child)};
    return strip_uri_scheme(child_uri);
}

[[nodiscard]]
static bool filename_has_coverage_prefixes(GjsCoverage* self,
                                           const char* filename) {
    auto* priv = static_cast<GjsCoveragePrivate*>(
        gjs_coverage_get_instance_private(self));
    Gjs::AutoChar workdir{g_get_current_dir()};
    Gjs::AutoChar abs_filename{g_canonicalize_filename(filename, workdir)};

    for (const char* const* prefix = priv->prefixes; *prefix; prefix++) {
        Gjs::AutoChar abs_prefix{g_canonicalize_filename(*prefix, workdir)};
        if (g_str_has_prefix(abs_filename, abs_prefix))
            return true;
    }
    return false;
}

[[nodiscard]]
static inline GErrorResult<> write_line(GOutputStream* out, const char* line) {
    Gjs::AutoError error;
    if (!g_output_stream_printf(out, nullptr, nullptr, error.out(), "%s\n",
                                line))
        return Err(error.release());
    return Ok{};
}

[[nodiscard]]
GErrorResult<Gjs::AutoUnref<GFile>> write_statistics_internal(GjsCoverage* self,
                                                              JSContext* cx) {
    if (!s_coverage_enabled) {
        g_critical(
            "Code coverage requested, but gjs_coverage_enable() was not called."
            " You must call this function before creating any GjsContext.");
        return Gjs::AutoUnref<GFile>{};
    }

    auto* priv = static_cast<GjsCoveragePrivate*>(
        gjs_coverage_get_instance_private(self));

    // Create output directory if it doesn't exist
    Gjs::AutoError error;
    if (!g_file_make_directory_with_parents(priv->output_dir, nullptr,
                                            error.out())) {
        if (!g_error_matches(error, G_IO_ERROR, G_IO_ERROR_EXISTS))
            return Err(error.release());
        error.reset();
    }

    GFile* output_file = g_file_get_child(priv->output_dir, "coverage.lcov");

    size_t lcov_length;
    JS::UniqueChars lcov = js::GetCodeCoverageSummary(cx, &lcov_length);

    Gjs::AutoUnref<GOutputStream> ostream{G_OUTPUT_STREAM(g_file_append_to(
        output_file, G_FILE_CREATE_NONE, nullptr, error.out()))};
    if (!ostream)
        return Err(error.release());

    Gjs::AutoStrv lcov_lines{g_strsplit(lcov.get(), "\n", -1)};
    const char* test_name = nullptr;
    bool ignoring_file = false;

    for (const char* const* iter = lcov_lines.get(); *iter; iter++) {
        if (ignoring_file) {
            if (strcmp(*iter, "end_of_record") == 0)
                ignoring_file = false;
            continue;
        }

        if (g_str_has_prefix(*iter, "TN:")) {
            /* Don't write the test name if the next line shows we are ignoring
             * the source file */
            test_name = *iter;
            continue;
        }

        if (g_str_has_prefix(*iter, "SF:")) {
            const char* filename = *iter + 3;
            if (!filename_has_coverage_prefixes(self, filename)) {
                ignoring_file = true;
                continue;
            }

            // Now we can write the test name before writing the source file
            MOZ_TRY(write_line(ostream, test_name));

            /* The source file could be a resource, so we must use
             * g_file_new_for_commandline_arg() to disambiguate between URIs and
             * filesystem paths. */
            Gjs::AutoUnref<GFile> source_file{
                g_file_new_for_commandline_arg(filename)};
            Gjs::AutoChar diverged_paths{
                find_diverging_child_components(source_file, priv->output_dir)};
            Gjs::AutoUnref<GFile> destination_file{
                g_file_resolve_relative_path(priv->output_dir, diverged_paths)};
            MOZ_TRY(copy_source_file_to_coverage_output(source_file,
                                                        destination_file));

            /* Rewrite the source file path to be relative to the output dir so
             * that genhtml will find it */
            MOZ_TRY(write_source_file_header(ostream, destination_file));
            continue;
        }

        MOZ_TRY(write_line(ostream, *iter));
    }

    return Gjs::AutoUnref<GFile>{output_file};
}

/**
 * gjs_coverage_write_statistics:
 * @self: A #GjsCoverage
 * @output_directory: A directory to write coverage information to.
 *
 * Scripts which were provided as part of the #GjsCoverage:prefixes construction
 * property will be written out to @output_directory, in the same directory
 * structure relative to the source dir where the tests were run.
 *
 * This function takes all available statistics and writes them out to either
 * the file provided or to files of the pattern (filename).info in the same
 * directory as the scanned files. It will provide coverage data for all files
 * ending with ".js" in the coverage directories.
 */
void gjs_coverage_write_statistics(GjsCoverage* self) {
    auto* priv = static_cast<GjsCoveragePrivate*>(
        gjs_coverage_get_instance_private(self));
    auto* cx = static_cast<JSContext*>(
        gjs_context_get_native_context(priv->coverage_context));
    Gjs::AutoMainRealm ar{cx};

    GErrorResult<Gjs::AutoUnref<GFile>> result{
        write_statistics_internal(self, cx)};
    if (result.isErr()) {
        g_critical("Error writing coverage data: %s",
                   result.inspectErr()->message);
        return;
    }

    Gjs::AutoChar output_file_path{g_file_get_path(result.unwrap())};
    g_message("Wrote coverage statistics to %s", output_file_path.get());
}

static void gjs_coverage_init(GjsCoverage*) {
    if (!s_coverage_enabled)
        g_critical(
            "Code coverage requested, but gjs_coverage_enable() was not called."
            " You must call this function before creating any GjsContext.");
}

static void coverage_tracer(JSTracer* trc, void* data) {
    GjsCoverage* self = GJS_COVERAGE(data);
    auto* priv = static_cast<GjsCoveragePrivate*>(
        gjs_coverage_get_instance_private(self));

    JS::TraceEdge<JSObject*>(trc, &priv->global, "Coverage global object");
}

GJS_JSAPI_RETURN_CONVENTION
static bool bootstrap_coverage(GjsCoverage* self) {
    auto* priv = static_cast<GjsCoveragePrivate*>(
        gjs_coverage_get_instance_private(self));

    auto* gjs = GjsContextPrivate::from_object(priv->coverage_context);
    JSContext* cx = gjs->context();

    JS::RootedObject debugger_global{
        cx, gjs_create_global_object(cx, GjsGlobalType::DEBUGGER)};
    {
        JSAutoRealm ar{cx, debugger_global};
        JS::RootedObject debuggee{cx, gjs->global()};
        if (!JS_WrapObject(cx, &debuggee))
            return false;

        JS::RootedValue v_debuggee{cx, JS::ObjectValue(*debuggee)};
        if (!JS_SetPropertyById(cx, debugger_global, gjs->atoms().debuggee(),
                                v_debuggee) ||
            !gjs_define_global_properties(cx, debugger_global,
                                          GjsGlobalType::DEBUGGER,
                                          "GJS coverage", "coverage"))
            return false;

        // Add a tracer, as suggested by jdm on #jsapi
        JS_AddExtraGCRootsTracer(cx, coverage_tracer, self);

        priv->global = debugger_global;
    }

    return true;
}

static void gjs_coverage_constructed(GObject* object) {
    G_OBJECT_CLASS(gjs_coverage_parent_class)->constructed(object);

    GjsCoverage* self = GJS_COVERAGE(object);
    auto* priv = static_cast<GjsCoveragePrivate*>(
        gjs_coverage_get_instance_private(self));
    new (&priv->global) JS::Heap<JSObject*>();

    if (!bootstrap_coverage(self)) {
        JSContext* cx = static_cast<JSContext*>(
            gjs_context_get_native_context(priv->coverage_context));
        Gjs::AutoMainRealm ar{cx};
        gjs_log_exception(cx);
    }
}

static void gjs_coverage_set_property(GObject* object, unsigned prop_id,
                                      const GValue* value,
                                      GParamSpec* pspec [[maybe_unused]]) {
    GjsCoverage* self = GJS_COVERAGE(object);
    auto* priv = static_cast<GjsCoveragePrivate*>(
        gjs_coverage_get_instance_private(self));
    switch (static_cast<GjsCoverageProps>(prop_id)) {
        case PROP_PREFIXES:
            g_assert(priv->prefixes == nullptr);
            priv->prefixes = static_cast<char**>(g_value_dup_boxed(value));
            break;
        case PROP_CONTEXT:
            priv->coverage_context = GJS_CONTEXT(g_value_dup_object(value));
            break;
        case PROP_CACHE:
            break;
        case PROP_OUTPUT_DIRECTORY:
            priv->output_dir = G_FILE(g_value_dup_object(value));
            break;
    }
}

static void gjs_coverage_dispose(GObject* object) {
    GjsCoverage* self = GJS_COVERAGE(object);
    auto* priv = static_cast<GjsCoveragePrivate*>(
        gjs_coverage_get_instance_private(self));

    /* Decomission objects inside of the JSContext before disposing of the
     * context */
    auto* cx = static_cast<JSContext*>(
        gjs_context_get_native_context(priv->coverage_context));
    JS_RemoveExtraGCRootsTracer(cx, coverage_tracer, self);
    priv->global = nullptr;

    g_clear_object(&priv->coverage_context);

    G_OBJECT_CLASS(gjs_coverage_parent_class)->dispose(object);
}

static void gjs_coverage_finalize(GObject* object) {
    GjsCoverage* self = GJS_COVERAGE(object);
    auto* priv = static_cast<GjsCoveragePrivate*>(
        gjs_coverage_get_instance_private(self));

    g_strfreev(priv->prefixes);
    g_clear_object(&priv->output_dir);
    priv->global.~Heap();

    G_OBJECT_CLASS(gjs_coverage_parent_class)->finalize(object);
}

static void gjs_coverage_class_init(GjsCoverageClass* klass) {
    GObjectClass* object_class = G_OBJECT_CLASS(klass);

    object_class->constructed = gjs_coverage_constructed;
    object_class->dispose = gjs_coverage_dispose;
    object_class->finalize = gjs_coverage_finalize;
    object_class->set_property = gjs_coverage_set_property;

    gjs_coverage_props[PROP_PREFIXES] = g_param_spec_boxed(
        "prefixes", "Prefixes",
        "Prefixes of files on which to perform coverage analysis", G_TYPE_STRV,
        GParamFlags(G_PARAM_CONSTRUCT_ONLY | G_PARAM_WRITABLE));
    gjs_coverage_props[PROP_CONTEXT] = g_param_spec_object(
        "context", "Context", "A context to gather coverage stats for",
        GJS_TYPE_CONTEXT,
        GParamFlags(G_PARAM_CONSTRUCT_ONLY | G_PARAM_WRITABLE));
    gjs_coverage_props[PROP_CACHE] = g_param_spec_object(
        "cache", "Deprecated property", "Has no effect", G_TYPE_FILE,
        GParamFlags(G_PARAM_CONSTRUCT_ONLY | G_PARAM_WRITABLE |
                    G_PARAM_DEPRECATED));
    gjs_coverage_props[PROP_OUTPUT_DIRECTORY] = g_param_spec_object(
        "output-directory", "Output directory",
        "Directory handle at which to output coverage statistics", G_TYPE_FILE,
        GParamFlags(G_PARAM_CONSTRUCT_ONLY | G_PARAM_WRITABLE |
                    G_PARAM_STATIC_STRINGS));

    g_object_class_install_properties(
        object_class, G_N_ELEMENTS(gjs_coverage_props), gjs_coverage_props);
}

/**
 * gjs_coverage_new:
 * @prefixes: A null-terminated strv of prefixes of files on which to record
 * code coverage
 * @coverage_context: A #GjsContext object
 * @output_dir: A #GFile handle to a directory in which to write coverage
 * information
 *
 * Creates a new #GjsCoverage object that collects coverage information for
 * any scripts run in @coverage_context.
 *
 * Scripts which were provided as part of @prefixes will be written out to
 * @output_dir, in the same directory structure relative to the source dir where
 * the tests were run.
 *
 * Returns: A #GjsCoverage object
 */
GjsCoverage* gjs_coverage_new(const char* const* prefixes,
                              GjsContext* coverage_context, GFile* output_dir) {
    return GJS_COVERAGE(g_object_new(GJS_TYPE_COVERAGE, "prefixes", prefixes,
                                     "context", coverage_context,
                                     "output-directory", output_dir, nullptr));
}

/**
 * gjs_coverage_enable:
 *
 * This function must be called before creating any #GjsContext, if you intend
 * to use any #GjsCoverage APIs.
 *
 * Since: 1.66
 */
void gjs_coverage_enable() {
    js::EnableCodeCoverage();
    s_coverage_enabled = true;
}
