package executor

import (
	"bytes"
	"context"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"sync"
	"time"

	"github.com/j3ssie/osmedeus/v5/internal/core"
	"github.com/j3ssie/osmedeus/v5/internal/runner"
	"github.com/j3ssie/osmedeus/v5/internal/template"
	"go.uber.org/zap"
)

// BashExecutor executes bash steps
type BashExecutor struct {
	templateEngine *template.Engine
	runner         runner.Runner
}

// NewBashExecutor creates a new bash executor
func NewBashExecutor(engine *template.Engine) *BashExecutor {
	return &BashExecutor{
		templateEngine: engine,
	}
}

// Name returns the executor name for logging/debugging
func (e *BashExecutor) Name() string {
	return "bash"
}

// StepTypes returns the step types this executor handles
func (e *BashExecutor) StepTypes() []core.StepType {
	return []core.StepType{core.StepTypeBash}
}

// SetRunner sets the runner for command execution
func (e *BashExecutor) SetRunner(r runner.Runner) {
	e.runner = r
}

// assembleCommand joins the command with structured args in order:
// command + speed_args + config_args + input_args + output_args
func assembleCommand(command, speedArgs, configArgs, inputArgs, outputArgs string) string {
	parts := []string{command}
	if speedArgs != "" {
		parts = append(parts, speedArgs)
	}
	if configArgs != "" {
		parts = append(parts, configArgs)
	}
	if inputArgs != "" {
		parts = append(parts, inputArgs)
	}
	if outputArgs != "" {
		parts = append(parts, outputArgs)
	}
	return strings.Join(parts, " ")
}

// writeStdFile writes command output to the specified file
func writeStdFile(path, content string) error {
	// Ensure parent directory exists
	if dir := filepath.Dir(path); dir != "" && dir != "." {
		if err := os.MkdirAll(dir, 0755); err != nil {
			return fmt.Errorf("failed to create directory: %w", err)
		}
	}
	return os.WriteFile(path, []byte(content), 0644)
}

// Execute executes a bash step
func (e *BashExecutor) Execute(ctx context.Context, step *core.Step, execCtx *core.ExecutionContext) (*core.StepResult, error) {
	result := &core.StepResult{
		StepName:  step.Name,
		Status:    core.StepStatusRunning,
		StartTime: time.Now(),
	}

	timeout, err := step.Timeout.Duration()
	if err != nil {
		result.Status = core.StepStatusFailed
		result.Error = err
		result.EndTime = time.Now()
		result.Duration = result.EndTime.Sub(result.StartTime)
		return result, err
	}

	var output string

	// Determine execution mode
	if len(step.ParallelCommands) > 0 {
		output, err = e.executeParallel(ctx, step.ParallelCommands, timeout)
	} else if len(step.Commands) > 0 {
		output, err = e.executeSequential(ctx, step.Commands, timeout)
	} else if step.Command != "" {
		// Assemble command with structured args if present
		finalCmd := assembleCommand(step.Command, step.SpeedArgs, step.ConfigArgs, step.InputArgs, step.OutputArgs)
		output, err = e.executeCommand(ctx, finalCmd, timeout)
	} else {
		err = fmt.Errorf("no command specified")
	}

	result.Output = output
	result.EndTime = time.Now()
	result.Duration = result.EndTime.Sub(result.StartTime)

	// Write stdout/stderr to file if std_file is specified
	if step.StdFile != "" {
		if writeErr := writeStdFile(step.StdFile, output); writeErr != nil {
			// Log warning but don't fail the step
			execCtx.Logger.Warn("Failed to write std_file",
				zap.String("path", step.StdFile),
				zap.Error(writeErr))
		}
	}

	if err != nil {
		result.Status = core.StepStatusFailed
		result.Error = err
		return result, err
	}

	result.Status = core.StepStatusSuccess
	return result, nil
}

// executeCommand executes a single command

func (e *BashExecutor) executeCommand(ctx context.Context, command string, timeout time.Duration) (string, error) {
	// Apply timeout if specified
	if timeout > 0 {
		var cancel context.CancelFunc
		ctx, cancel = context.WithTimeout(ctx, timeout)
		defer cancel()
	}

	// Use runner if available, otherwise fall back to local execution
	if e.runner != nil {
		result, err := e.runner.Execute(ctx, command)
		if err != nil {
			if ctx.Err() == context.DeadlineExceeded {
				return result.Output, fmt.Errorf("command timed out after %s", timeout)
			}
			return result.Output, fmt.Errorf("command failed: %w", err)
		}
		if result.ExitCode != 0 {
			return result.Output, fmt.Errorf("command exited with code %d", result.ExitCode)
		}
		return strings.TrimSpace(result.Output), nil
	}

	// Fallback to local execution
	// @NOTE: yes yes, I know this is a security risk. This is the intended behavior.
	cmd := exec.CommandContext(ctx, "sh", "-c", command)

	var stdout, stderr bytes.Buffer
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr

	err := cmd.Run()

	output := stdout.String()
	if stderr.Len() > 0 {
		output += "\n" + stderr.String()
	}

	if err != nil {
		if ctx.Err() == context.DeadlineExceeded {
			return output, fmt.Errorf("command timed out after %s", timeout)
		}
		return output, fmt.Errorf("command failed: %w\nstderr: %s", err, stderr.String())
	}

	return strings.TrimSpace(output), nil
}

// executeSequential executes commands sequentially
func (e *BashExecutor) executeSequential(ctx context.Context, commands []string, timeout time.Duration) (string, error) {
	var outputs []string

	for _, cmd := range commands {
		output, err := e.executeCommand(ctx, cmd, timeout)
		outputs = append(outputs, output)
		if err != nil {
			return strings.Join(outputs, "\n"), err
		}
	}

	return strings.Join(outputs, "\n"), nil
}

// executeParallel executes commands in parallel
func (e *BashExecutor) executeParallel(ctx context.Context, commands []string, timeout time.Duration) (string, error) {
	type result struct {
		index  int
		output string
		err    error
	}

	results := make(chan result, len(commands))
	var wg sync.WaitGroup

	for i, cmd := range commands {
		wg.Add(1)
		go func(idx int, command string) {
			defer wg.Done()
			output, err := e.executeCommand(ctx, command, timeout)
			results <- result{index: idx, output: output, err: err}
		}(i, cmd)
	}

	// Wait for all commands to complete
	go func() {
		wg.Wait()
		close(results)
	}()

	// Collect results
	outputs := make([]string, len(commands))
	var firstError error

	for r := range results {
		outputs[r.index] = r.output
		if r.err != nil && firstError == nil {
			firstError = r.err
		}
	}

	return strings.Join(outputs, "\n"), firstError
}

// CanHandle returns true if this executor can handle the given step type
func (e *BashExecutor) CanHandle(stepType core.StepType) bool {
	return stepType == core.StepTypeBash
}