// Copyright 2019 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Package modules provides a client that can be used to manage Hugo Components,
// what's referred to as Hugo Modules. Hugo Modules is built on top of Go Modules,
// but also supports vendoring and components stored directly in the themes dir.
package modules

import (
	"net/url"
	"time"

	"github.com/gohugoio/hugo/config"
)

var _ Module = (*moduleAdapter)(nil)

type Module interface {
	// Optional config read from the configFilename above.
	Cfg() config.Provider

	// The decoded module config and mounts.
	Config() Config

	// Optional configuration filenames (e.g. "/themes/mytheme/config.json").
	// This will be added to the special configuration watch list when in
	// server mode.
	ConfigFilenames() []string

	// Directory holding files for this module.
	Dir() string

	// Returns whether this is a Go Module.
	IsGoMod() bool

	// Any directory remappings.
	Mounts() []Mount

	// In the dependency tree, this is the first module that defines this module
	// as a dependency.
	Owner() Module

	// Returns the path to this module.
	// This will either be the module path, e.g. "github.com/gohugoio/myshortcodes",
	// or the path below your /theme folder, e.g. "mytheme".
	Path() string

	// For direct dependencies, this will be Path + "@" + VersionQuery.
	// For managed dependencies, this will be the same as Path.
	PathVersionQuery(escapeQuery bool) string

	// Replaced by this module.
	Replace() Module

	// Returns whether Dir points below the _vendor dir.
	Vendor() bool

	// The module version.
	Version() string

	// The version query requested in the import.
	VersionQuery() string

	// Checksum for path, version
	Sum() string

	// Time version was created.
	Time() time.Time

	// Whether this module's dir is a watch candidate.
	Watch() bool

	// Origin returns the module's origin info if available (VCS, URL, Hash, etc.).
	Origin() ModuleOrigin
}

// ModuleOrigin contains origin info for a Go module.
type ModuleOrigin struct {
	VCS  string // version control system, e.g. "git"
	URL  string // repository URL, e.g. "https://github.com/bep/hugo-testing-git-versions"
	Hash string // commit hash
	Ref  string // e.g. "refs/tags/v3.0.1"
}

func (o ModuleOrigin) IsZero() bool {
	return o.URL == ""
}

type Modules []Module

type moduleAdapter struct {
	path         string
	dir          string
	version      string
	versionQuery string
	vendor       bool
	projectMod   bool
	owner        Module

	mounts []Mount

	configFilenames []string
	cfg             config.Provider
	config          Config

	// Set if a Go module.
	gomod *goModule
}

func (m *moduleAdapter) Cfg() config.Provider {
	return m.cfg
}

func (m *moduleAdapter) Config() Config {
	return m.config
}

func (m *moduleAdapter) ConfigFilenames() []string {
	return m.configFilenames
}

func (m *moduleAdapter) Dir() string {
	// This may point to the _vendor dir.
	if !m.IsGoMod() || m.dir != "" {
		return m.dir
	}
	return m.gomod.Dir
}

func (m *moduleAdapter) IsGoMod() bool {
	return m.gomod != nil
}

func (m *moduleAdapter) Mounts() []Mount {
	return m.mounts
}

func (m *moduleAdapter) Owner() Module {
	return m.owner
}

func (m *moduleAdapter) Path() string {
	if !m.IsGoMod() || m.path != "" {
		return m.path
	}
	return m.gomod.Path
}

func (m *moduleAdapter) PathVersionQuery(escapeQuery bool) string {
	// We added version as a config option in Hugo v0.150.0, so
	// to make this backward compatible, we only add the version
	// if it was explicitly requested.
	pathBase := m.Path()
	if m.versionQuery == "" || !m.IsGoMod() {
		return pathBase
	}

	q := m.versionQuery
	if escapeQuery {
		q = url.QueryEscape(q)
	}

	return pathBase + "@" + q
}

func (m *moduleAdapter) Replace() Module {
	if m.IsGoMod() && !m.Vendor() && m.gomod.Replace != nil {
		return &moduleAdapter{
			gomod: m.gomod.Replace,
			owner: m.owner,
		}
	}
	return nil
}

func (m *moduleAdapter) Vendor() bool {
	return m.vendor
}

func (m *moduleAdapter) Version() string {
	if !m.IsGoMod() || m.version != "" {
		return m.version
	}
	return m.gomod.Version
}

func (m *moduleAdapter) VersionQuery() string {
	return m.versionQuery
}

func (m *moduleAdapter) Sum() string {
	if !m.IsGoMod() {
		return ""
	}

	return m.gomod.Sum
}

func (m *moduleAdapter) Time() time.Time {
	if !m.IsGoMod() || m.gomod.Time == nil {
		return time.Time{}
	}

	return *m.gomod.Time
}

func (m *moduleAdapter) Watch() bool {
	if m.Owner() == nil {
		// Main project
		return true
	}

	if !m.IsGoMod() {
		// Module inside /themes
		return true
	}

	if m.Replace() != nil {
		// Version is not set when replaced by a local folder.
		return m.Replace().Version() == ""
	}

	// Any module set up in a workspace file will have Indirect set to false.
	// That leaves modules inside the read-only module cache.
	return !m.gomod.Indirect
}

func (m *moduleAdapter) Origin() ModuleOrigin {
	if !m.IsGoMod() || m.gomod.Origin == nil {
		return ModuleOrigin{}
	}
	return ModuleOrigin{
		VCS:  m.gomod.Origin.VCS,
		URL:  m.gomod.Origin.URL,
		Hash: m.gomod.Origin.Hash,
		Ref:  m.gomod.Origin.Ref,
	}
}
