// Copyright 2018 Google Inc. 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 android

import (
	"fmt"
	"sort"
	"strings"

	"github.com/google/blueprint"
	"github.com/google/blueprint/proptools"
)

// RuleBuilder provides an alternative to ModuleContext.Rule and ModuleContext.Build to add a command line to the build
// graph.
type RuleBuilder struct {
	commands       []*RuleBuilderCommand
	installs       RuleBuilderInstalls
	temporariesSet map[WritablePath]bool
	restat         bool
	missingDeps    []string
}

// NewRuleBuilder returns a newly created RuleBuilder.
func NewRuleBuilder() *RuleBuilder {
	return &RuleBuilder{
		temporariesSet: make(map[WritablePath]bool),
	}
}

// RuleBuilderInstall is a tuple of install from and to locations.
type RuleBuilderInstall struct {
	From Path
	To   string
}

type RuleBuilderInstalls []RuleBuilderInstall

// String returns the RuleBuilderInstalls in the form used by $(call copy-many-files) in Make, a space separated
// list of from:to tuples.
func (installs RuleBuilderInstalls) String() string {
	sb := strings.Builder{}
	for i, install := range installs {
		if i != 0 {
			sb.WriteRune(' ')
		}
		sb.WriteString(install.From.String())
		sb.WriteRune(':')
		sb.WriteString(install.To)
	}
	return sb.String()
}

// MissingDeps adds modules to the list of missing dependencies.  If MissingDeps
// is called with a non-empty input, any call to Build will result in a rule
// that will print an error listing the missing dependencies and fail.
// MissingDeps should only be called if Config.AllowMissingDependencies() is
// true.
func (r *RuleBuilder) MissingDeps(missingDeps []string) {
	r.missingDeps = append(r.missingDeps, missingDeps...)
}

// Restat marks the rule as a restat rule, which will be passed to ModuleContext.Rule in BuildParams.Restat.
func (r *RuleBuilder) Restat() *RuleBuilder {
	r.restat = true
	return r
}

// Install associates an output of the rule with an install location, which can be retrieved later using
// RuleBuilder.Installs.
func (r *RuleBuilder) Install(from Path, to string) {
	r.installs = append(r.installs, RuleBuilderInstall{from, to})
}

// Command returns a new RuleBuilderCommand for the rule.  The commands will be ordered in the rule by when they were
// created by this method.  That can be mutated through their methods in any order, as long as the mutations do not
// race with any call to Build.
func (r *RuleBuilder) Command() *RuleBuilderCommand {
	command := &RuleBuilderCommand{}
	r.commands = append(r.commands, command)
	return command
}

// Temporary marks an output of a command as an intermediate file that will be used as an input to another command
// in the same rule, and should not be listed in Outputs.
func (r *RuleBuilder) Temporary(path WritablePath) {
	r.temporariesSet[path] = true
}

// DeleteTemporaryFiles adds a command to the rule that deletes any outputs that have been marked using Temporary
// when the rule runs.  DeleteTemporaryFiles should be called after all calls to Temporary.
func (r *RuleBuilder) DeleteTemporaryFiles() {
	var temporariesList WritablePaths

	for intermediate := range r.temporariesSet {
		temporariesList = append(temporariesList, intermediate)
	}

	sort.Slice(temporariesList, func(i, j int) bool {
		return temporariesList[i].String() < temporariesList[j].String()
	})

	r.Command().Text("rm").Flag("-f").Outputs(temporariesList)
}

// Inputs returns the list of paths that were passed to the RuleBuilderCommand methods that take input paths, such
// as RuleBuilderCommand.Input, RuleBuilderComand.Implicit, or RuleBuilderCommand.FlagWithInput.  Inputs to a command
// that are also outputs of another command in the same RuleBuilder are filtered out.
func (r *RuleBuilder) Inputs() Paths {
	outputs := r.outputSet()

	inputs := make(map[string]Path)
	for _, c := range r.commands {
		for _, input := range c.inputs {
			if _, isOutput := outputs[input.String()]; !isOutput {
				inputs[input.String()] = input
			}
		}
	}

	var inputList Paths
	for _, input := range inputs {
		inputList = append(inputList, input)
	}

	sort.Slice(inputList, func(i, j int) bool {
		return inputList[i].String() < inputList[j].String()
	})

	return inputList
}

func (r *RuleBuilder) outputSet() map[string]WritablePath {
	outputs := make(map[string]WritablePath)
	for _, c := range r.commands {
		for _, output := range c.outputs {
			outputs[output.String()] = output
		}
	}
	return outputs
}

// Outputs returns the list of paths that were passed to the RuleBuilderCommand methods that take output paths, such
// as RuleBuilderCommand.Output, RuleBuilderCommand.ImplicitOutput, or RuleBuilderCommand.FlagWithInput.
func (r *RuleBuilder) Outputs() WritablePaths {
	outputs := r.outputSet()

	var outputList WritablePaths
	for _, output := range outputs {
		if !r.temporariesSet[output] {
			outputList = append(outputList, output)
		}
	}

	sort.Slice(outputList, func(i, j int) bool {
		return outputList[i].String() < outputList[j].String()
	})

	return outputList
}

// Installs returns the list of tuples passed to Install.
func (r *RuleBuilder) Installs() RuleBuilderInstalls {
	return append(RuleBuilderInstalls(nil), r.installs...)
}

func (r *RuleBuilder) toolsSet() map[string]Path {
	tools := make(map[string]Path)
	for _, c := range r.commands {
		for _, tool := range c.tools {
			tools[tool.String()] = tool
		}
	}

	return tools
}

// Tools returns the list of paths that were passed to the RuleBuilderCommand.Tool method.
func (r *RuleBuilder) Tools() Paths {
	toolsSet := r.toolsSet()

	var toolsList Paths
	for _, tool := range toolsSet {
		toolsList = append(toolsList, tool)
	}

	sort.Slice(toolsList, func(i, j int) bool {
		return toolsList[i].String() < toolsList[j].String()
	})

	return toolsList
}

// Commands returns a slice containing a the built command line for each call to RuleBuilder.Command.
func (r *RuleBuilder) Commands() []string {
	var commands []string
	for _, c := range r.commands {
		commands = append(commands, string(c.buf))
	}
	return commands
}

// BuilderContext is a subset of ModuleContext and SingletonContext.
type BuilderContext interface {
	PathContext
	Rule(PackageContext, string, blueprint.RuleParams, ...string) blueprint.Rule
	Build(PackageContext, BuildParams)
}

var _ BuilderContext = ModuleContext(nil)
var _ BuilderContext = SingletonContext(nil)

// Build adds the built command line to the build graph, with dependencies on Inputs and Tools, and output files for
// Outputs.
func (r *RuleBuilder) Build(pctx PackageContext, ctx BuilderContext, name string, desc string) {
	if len(r.missingDeps) > 0 {
		ctx.Build(pctx, BuildParams{
			Rule:        ErrorRule,
			Outputs:     r.Outputs(),
			Description: desc,
			Args: map[string]string{
				"error": "missing dependencies: " + strings.Join(r.missingDeps, ", "),
			},
		})
		return
	}

	if len(r.Commands()) > 0 {
		ctx.Build(pctx, BuildParams{
			Rule: ctx.Rule(pctx, name, blueprint.RuleParams{
				Command:     strings.Join(proptools.NinjaEscapeList(r.Commands()), " && "),
				CommandDeps: r.Tools().Strings(),
			}),
			Implicits:   r.Inputs(),
			Outputs:     r.Outputs(),
			Description: desc,
		})
	}
}

// RuleBuilderCommand is a builder for a command in a command line.  It can be mutated by its methods to add to the
// command and track dependencies.  The methods mutate the RuleBuilderCommand in place, as well as return the
// RuleBuilderCommand, so they can be used chained or unchained.  All methods that add text implicitly add a single
// space as a separator from the previous method.
type RuleBuilderCommand struct {
	buf     []byte
	inputs  Paths
	outputs WritablePaths
	tools   Paths
}

// Text adds the specified raw text to the command line.  The text should not contain input or output paths or the
// rule will not have them listed in its dependencies or outputs.
func (c *RuleBuilderCommand) Text(text string) *RuleBuilderCommand {
	if len(c.buf) > 0 {
		c.buf = append(c.buf, ' ')
	}
	c.buf = append(c.buf, text...)
	return c
}

// Textf adds the specified formatted text to the command line.  The text should not contain input or output paths or
// the rule will not have them listed in its dependencies or outputs.
func (c *RuleBuilderCommand) Textf(format string, a ...interface{}) *RuleBuilderCommand {
	return c.Text(fmt.Sprintf(format, a...))
}

// Flag adds the specified raw text to the command line.  The text should not contain input or output paths or the
// rule will not have them listed in its dependencies or outputs.
func (c *RuleBuilderCommand) Flag(flag string) *RuleBuilderCommand {
	return c.Text(flag)
}

// FlagWithArg adds the specified flag and argument text to the command line, with no separator between them.  The flag
// and argument should not contain input or output paths or the rule will not have them listed in its dependencies or
// outputs.
func (c *RuleBuilderCommand) FlagWithArg(flag, arg string) *RuleBuilderCommand {
	return c.Text(flag + arg)
}

// FlagForEachArg adds the specified flag joined with each argument to the command line.  The result is identical to
// calling FlagWithArg for argument.
func (c *RuleBuilderCommand) FlagForEachArg(flag string, args []string) *RuleBuilderCommand {
	for _, arg := range args {
		c.FlagWithArg(flag, arg)
	}
	return c
}

// FlagWithList adds the specified flag and list of arguments to the command line, with the arguments joined by sep
// and no separator between the flag and arguments.  The flag and arguments should not contain input or output paths or
// the rule will not have them listed in its dependencies or outputs.
func (c *RuleBuilderCommand) FlagWithList(flag string, list []string, sep string) *RuleBuilderCommand {
	return c.Text(flag + strings.Join(list, sep))
}

// Tool adds the specified tool path to the command line.  The path will be also added to the dependencies returned by
// RuleBuilder.Tools.
func (c *RuleBuilderCommand) Tool(path Path) *RuleBuilderCommand {
	c.tools = append(c.tools, path)
	return c.Text(path.String())
}

// Input adds the specified input path to the command line.  The path will also be added to the dependencies returned by
// RuleBuilder.Inputs.
func (c *RuleBuilderCommand) Input(path Path) *RuleBuilderCommand {
	c.inputs = append(c.inputs, path)
	return c.Text(path.String())
}

// Inputs adds the specified input paths to the command line, separated by spaces.  The paths will also be added to the
// dependencies returned by RuleBuilder.Inputs.
func (c *RuleBuilderCommand) Inputs(paths Paths) *RuleBuilderCommand {
	for _, path := range paths {
		c.Input(path)
	}
	return c
}

// Implicit adds the specified input path to the dependencies returned by RuleBuilder.Inputs without modifying the
// command line.
func (c *RuleBuilderCommand) Implicit(path Path) *RuleBuilderCommand {
	c.inputs = append(c.inputs, path)
	return c
}

// Implicits adds the specified input paths to the dependencies returned by RuleBuilder.Inputs without modifying the
// command line.
func (c *RuleBuilderCommand) Implicits(paths Paths) *RuleBuilderCommand {
	c.inputs = append(c.inputs, paths...)
	return c
}

// Output adds the specified output path to the command line.  The path will also be added to the outputs returned by
// RuleBuilder.Outputs.
func (c *RuleBuilderCommand) Output(path WritablePath) *RuleBuilderCommand {
	c.outputs = append(c.outputs, path)
	return c.Text(path.String())
}

// Outputs adds the specified output paths to the command line, separated by spaces.  The paths will also be added to
// the outputs returned by RuleBuilder.Outputs.
func (c *RuleBuilderCommand) Outputs(paths WritablePaths) *RuleBuilderCommand {
	for _, path := range paths {
		c.Output(path)
	}
	return c
}

// ImplicitOutput adds the specified output path to the dependencies returned by RuleBuilder.Outputs without modifying
// the command line.
func (c *RuleBuilderCommand) ImplicitOutput(path WritablePath) *RuleBuilderCommand {
	c.outputs = append(c.outputs, path)
	return c
}

// ImplicitOutputs adds the specified output paths to the dependencies returned by RuleBuilder.Outputs without modifying
// the command line.
func (c *RuleBuilderCommand) ImplicitOutputs(paths WritablePaths) *RuleBuilderCommand {
	c.outputs = append(c.outputs, paths...)
	return c
}

// FlagWithInput adds the specified flag and input path to the command line, with no separator between them.  The path
// will also be added to the dependencies returned by RuleBuilder.Inputs.
func (c *RuleBuilderCommand) FlagWithInput(flag string, path Path) *RuleBuilderCommand {
	c.inputs = append(c.inputs, path)
	return c.Text(flag + path.String())
}

// FlagWithInputList adds the specified flag and input paths to the command line, with the inputs joined by sep
// and no separator between the flag and inputs.  The input paths will also be added to the dependencies returned by
// RuleBuilder.Inputs.
func (c *RuleBuilderCommand) FlagWithInputList(flag string, paths Paths, sep string) *RuleBuilderCommand {
	c.inputs = append(c.inputs, paths...)
	return c.FlagWithList(flag, paths.Strings(), sep)
}

// FlagForEachInput adds the specified flag joined with each input path to the command line.  The input paths will also
// be added to the dependencies returned by RuleBuilder.Inputs.  The result is identical to calling FlagWithInput for
// each input path.
func (c *RuleBuilderCommand) FlagForEachInput(flag string, paths Paths) *RuleBuilderCommand {
	for _, path := range paths {
		c.FlagWithInput(flag, path)
	}
	return c
}

// FlagWithOutput adds the specified flag and output path to the command line, with no separator between them.  The path
// will also be added to the outputs returned by RuleBuilder.Outputs.
func (c *RuleBuilderCommand) FlagWithOutput(flag string, path WritablePath) *RuleBuilderCommand {
	c.outputs = append(c.outputs, path)
	return c.Text(flag + path.String())
}

// String returns the command line.
func (c *RuleBuilderCommand) String() string {
	return string(c.buf)
}