package task

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"slices"
	"strings"
	"sync"

	"github.com/Masterminds/semver/v3"
	"github.com/sajari/fuzzy"

	"github.com/go-task/task/v3/errors"
	"github.com/go-task/task/v3/internal/compiler"
	"github.com/go-task/task/v3/internal/execext"
	"github.com/go-task/task/v3/internal/filepathext"
	"github.com/go-task/task/v3/internal/logger"
	"github.com/go-task/task/v3/internal/output"
	"github.com/go-task/task/v3/internal/version"
	"github.com/go-task/task/v3/taskfile"
	"github.com/go-task/task/v3/taskfile/ast"
)

func (e *Executor) Setup() error {
	e.setupLogger()
	node, err := e.getRootNode()
	if err != nil {
		return err
	}
	if err := e.setupTempDir(); err != nil {
		return err
	}
	if err := e.readTaskfile(node); err != nil {
		return err
	}
	e.setupFuzzyModel()
	e.setupStdFiles()
	if err := e.setupOutput(); err != nil {
		return err
	}
	if err := e.setupCompiler(); err != nil {
		return err
	}
	if err := e.readDotEnvFiles(); err != nil {
		return err
	}
	if err := e.doVersionChecks(); err != nil {
		return err
	}
	e.setupDefaults()
	e.setupConcurrencyState()
	return nil
}

func (e *Executor) getRootNode() (taskfile.Node, error) {
	node, err := taskfile.NewRootNode(e.Logger, e.Entrypoint, e.Dir, e.Insecure, e.Timeout)
	if err != nil {
		return nil, err
	}
	e.Dir = node.Dir()
	return node, err
}

func (e *Executor) readTaskfile(node taskfile.Node) error {
	reader := taskfile.NewReader(
		node,
		e.Insecure,
		e.Download,
		e.Offline,
		e.Timeout,
		e.TempDir.Remote,
		e.Logger,
	)
	graph, err := reader.Read()
	if err != nil {
		return err
	}
	if e.Taskfile, err = graph.Merge(); err != nil {
		return err
	}
	return nil
}

func (e *Executor) setupFuzzyModel() {
	if e.Taskfile != nil {
		return
	}

	model := fuzzy.NewModel()
	model.SetThreshold(1) // because we want to build grammar based on every task name

	var words []string
	for _, taskName := range e.Taskfile.Tasks.Keys() {
		words = append(words, taskName)

		for _, task := range e.Taskfile.Tasks.Values() {
			words = slices.Concat(words, task.Aliases)
		}
	}

	model.Train(words)
	e.fuzzyModel = model
}

func (e *Executor) setupTempDir() error {
	if e.TempDir != (TempDir{}) {
		return nil
	}

	if os.Getenv("TASK_TEMP_DIR") == "" {
		e.TempDir = TempDir{
			Remote:      filepathext.SmartJoin(e.Dir, ".task"),
			Fingerprint: filepathext.SmartJoin(e.Dir, ".task"),
		}
	} else if filepath.IsAbs(os.Getenv("TASK_TEMP_DIR")) || strings.HasPrefix(os.Getenv("TASK_TEMP_DIR"), "~") {
		tempDir, err := execext.Expand(os.Getenv("TASK_TEMP_DIR"))
		if err != nil {
			return err
		}
		projectDir, _ := filepath.Abs(e.Dir)
		projectName := filepath.Base(projectDir)
		e.TempDir = TempDir{
			Remote:      tempDir,
			Fingerprint: filepathext.SmartJoin(tempDir, projectName),
		}

	} else {
		e.TempDir = TempDir{
			Remote:      filepathext.SmartJoin(e.Dir, os.Getenv("TASK_TEMP_DIR")),
			Fingerprint: filepathext.SmartJoin(e.Dir, os.Getenv("TASK_TEMP_DIR")),
		}
	}

	if os.Getenv("TASK_REMOTE_DIR") != "" {
		if filepath.IsAbs(os.Getenv("TASK_REMOTE_DIR")) || strings.HasPrefix(os.Getenv("TASK_REMOTE_DIR"), "~") {
			remoteTempDir, err := execext.Expand(os.Getenv("TASK_REMOTE_DIR"))
			if err != nil {
				return err
			}
			e.TempDir.Remote = remoteTempDir
		} else {
			e.TempDir.Remote = filepathext.SmartJoin(e.Dir, ".task")
		}
	}

	return nil
}

func (e *Executor) setupStdFiles() {
	if e.Stdin == nil {
		e.Stdin = os.Stdin
	}
	if e.Stdout == nil {
		e.Stdout = os.Stdout
	}
	if e.Stderr == nil {
		e.Stderr = os.Stderr
	}
}

func (e *Executor) setupLogger() {
	e.Logger = &logger.Logger{
		Stdin:      e.Stdin,
		Stdout:     e.Stdout,
		Stderr:     e.Stderr,
		Verbose:    e.Verbose,
		Color:      e.Color,
		AssumeYes:  e.AssumeYes,
		AssumeTerm: e.AssumeTerm,
	}
}

func (e *Executor) setupOutput() error {
	if !e.OutputStyle.IsSet() {
		e.OutputStyle = e.Taskfile.Output
	}

	var err error
	e.Output, err = output.BuildFor(&e.OutputStyle, e.Logger)
	return err
}

func (e *Executor) setupCompiler() error {
	if e.UserWorkingDir == "" {
		var err error
		e.UserWorkingDir, err = os.Getwd()
		if err != nil {
			return err
		}
	}

	e.Compiler = &compiler.Compiler{
		Dir:            e.Dir,
		Entrypoint:     e.Entrypoint,
		UserWorkingDir: e.UserWorkingDir,
		TaskfileEnv:    e.Taskfile.Env,
		TaskfileVars:   e.Taskfile.Vars,
		Logger:         e.Logger,
	}
	return nil
}

func (e *Executor) readDotEnvFiles() error {
	if e.Taskfile.Version.LessThan(ast.V3) {
		return nil
	}

	env, err := taskfile.Dotenv(e.Compiler, e.Taskfile, e.Dir)
	if err != nil {
		return err
	}

	err = env.Range(func(key string, value ast.Var) error {
		if _, ok := e.Taskfile.Env.Get(key); !ok {
			e.Taskfile.Env.Set(key, value)
		}
		return nil
	})
	return err
}

func (e *Executor) setupDefaults() {
	if e.Taskfile.Method == "" {
		e.Taskfile.Method = "checksum"
	}
	if e.Taskfile.Run == "" {
		e.Taskfile.Run = "always"
	}
}

func (e *Executor) setupConcurrencyState() {
	e.executionHashes = make(map[string]context.Context)

	e.taskCallCount = make(map[string]*int32, e.Taskfile.Tasks.Len())
	e.mkdirMutexMap = make(map[string]*sync.Mutex, e.Taskfile.Tasks.Len())
	for _, k := range e.Taskfile.Tasks.Keys() {
		e.taskCallCount[k] = new(int32)
		e.mkdirMutexMap[k] = &sync.Mutex{}
	}

	if e.Concurrency > 0 {
		e.concurrencySemaphore = make(chan struct{}, e.Concurrency)
	}
}

func (e *Executor) doVersionChecks() error {
	// Copy the version to avoid modifying the original
	schemaVersion := &semver.Version{}
	*schemaVersion = *e.Taskfile.Version

	// Error if the Taskfile uses a schema version below v3
	if schemaVersion.LessThan(ast.V3) {
		return &errors.TaskfileVersionCheckError{
			URI:           e.Taskfile.Location,
			SchemaVersion: schemaVersion,
			Message:       `no longer supported. Please use v3 or above`,
		}
	}

	// Get the current version of Task
	// If we can't parse the version (e.g. when its "devel"), then ignore the current version checks
	currentVersion, err := semver.NewVersion(version.GetVersion())
	if err != nil {
		return nil
	}

	// Error if the Taskfile uses a schema version above the current version of Task
	if schemaVersion.GreaterThan(currentVersion) {
		return &errors.TaskfileVersionCheckError{
			URI:           e.Taskfile.Location,
			SchemaVersion: schemaVersion,
			Message:       fmt.Sprintf(`is greater than the current version of Task (%s)`, currentVersion.String()),
		}
	}

	return nil
}