package job_compilers

/* ***** BEGIN GPL LICENSE BLOCK *****
 *
 * Original Code Copyright (C) 2022 Blender Foundation.
 *
 * This file is part of Flamenco.
 *
 * Flamenco is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 *
 * Flamenco is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * Flamenco.  If not, see <https://www.gnu.org/licenses/>.
 *
 * ***** END GPL LICENSE BLOCK ***** */

import (
	"errors"
	"time"

	"github.com/dop251/goja"
	"github.com/dop251/goja_nodejs/require"
	"github.com/google/uuid"
	"github.com/rs/zerolog/log"
)

var ErrJobTypeUnknown = errors.New("job type unknown")
var ErrScriptIncomplete = errors.New("job compiler script incomplete")

type GojaJobCompiler struct {
	jobtypes map[string]JobType // Mapping from job type name to jobType struct.
	registry *require.Registry  // Goja module registry.
}

type JobType struct {
	program  *goja.Program // Compiled JavaScript file.
	filename string        // The filename of that JS file.
}

func Load() (*GojaJobCompiler, error) {
	compiler := GojaJobCompiler{
		jobtypes: map[string]JobType{},
	}

	if err := compiler.loadScripts(); err != nil {
		return nil, err
	}

	staticFileLoader := func(path string) ([]byte, error) {
		content, err := compiler.loadScript(path)
		if err != nil {
			// The 'require' module uses this to try different variations of the path
			// in order to find it (without .js, with .js, etc.), so don't log any of
			// such errors.
			return nil, require.ModuleFileDoesNotExistError
		}
		return content, nil
	}

	compiler.registry = require.NewRegistry(require.WithLoader(staticFileLoader))
	compiler.registry.RegisterNativeModule("author", AuthorModule)
	compiler.registry.RegisterNativeModule("path", PathModule)
	compiler.registry.RegisterNativeModule("process", ProcessModule)

	return &compiler, nil
}

func (c *GojaJobCompiler) newGojaVM() *goja.Runtime {
	vm := goja.New()
	vm.SetFieldNameMapper(goja.UncapFieldNameMapper())

	mustSet := func(name string, value interface{}) {
		err := vm.Set(name, value)
		if err != nil {
			log.Panic().Err(err).Msgf("unable to register '%s' in Goja VM", name)
		}
	}

	// Set some global functions for script debugging purposes.
	mustSet("print", jsPrint)
	mustSet("alert", jsAlert)

	// Pre-import some useful modules.
	c.registry.Enable(vm)
	mustSet("author", require.Require(vm, "author"))
	mustSet("path", require.Require(vm, "path"))
	mustSet("process", require.Require(vm, "process"))

	return vm
}

func (c *GojaJobCompiler) Run(jobTypeName string) error {
	jobType, ok := c.jobtypes[jobTypeName]
	if !ok {
		return ErrJobTypeUnknown
	}

	created, err := time.Parse(time.RFC3339, "2022-01-03T18:53:00+01:00")
	if err != nil {
		panic("hard-coded timestamp is wrong")
	}

	job := AuthoredJob{
		JobID:    uuid.New().String(),
		JobType:  "blender-render",
		Priority: 50,
		Name:     "190_0030_A.lighting",
		Created:  created,
		Settings: JobSettings{
			"blender_cmd":           "{blender}",
			"chunk_size":            5,
			"frames":                "101-172",
			"render_output":         "{render}/sprites/farm_output/shots/190_credits/190_0030_A/190_0030_A.lighting/######",
			"fps":                   24.0,
			"extract_audio":         false,
			"images_or_video":       "images",
			"format":                "JPG",
			"output_file_extension": ".jpg",
			"filepath":              "{shaman}/65/61672427b63a96392cd72d65/pro/shots/190_credits/190_0030_A/190_0030_A.lighting.flamenco.blend",
		},
		Metadata: JobMetadata{
			"user":    "Sybren A. Stüvel <sybren@blender.org>",
			"project": "Sprøte Frøte",
		},
	}

	vm := c.newGojaVM()

	// This should register the `compileJob()` function called below:
	if _, err := vm.RunProgram(jobType.program); err != nil {
		return err
	}

	compileJob, isCallable := goja.AssertFunction(vm.Get("compileJob"))
	if !isCallable {
		log.Error().
			Str("jobType", jobTypeName).
			Str("script", jobType.filename).
			Msg("script does not define a compileJob(job) function")
		return ErrScriptIncomplete

	}

	if _, err := compileJob(nil, vm.ToValue(&job)); err != nil {
		return err
	}

	log.Info().
		Int("tasks", len(job.Tasks)).
		Str("name", job.Name).
		Str("jobtype", job.JobType).
		Msg("job created")

	return nil
}