// Copyright 2024 Matthew Rich <matthewrich.conf@gmail.com>. All rights reserved.

package command

import (
_	"context"
	"fmt"
	"errors"
	"io"
	"log/slog"
_	"net/url"
	"os/exec"
	"strings"
	"text/template"
	"decl/internal/codec"
	"syscall"
)

// A resource that implements the ExecProvider interface can be used as an exec target.
type CommandProvider interface {
	Start() error
	Wait() error
	SetCmdEnv([]string)
	SetStdin(io.Reader)
	StdinPipe() (io.WriteCloser, error)
	StdoutPipe() (io.ReadCloser, error)
	StderrPipe() (io.ReadCloser, error)
}

var ErrUnknownCommand error = errors.New("Unable to find command in path")

type CommandExecutor func(value any) ([]byte, error)
type CommandExtractAttributes func(output []byte, target any) error
type CommandExists func() error

type CommandInput string

type Command struct {
	Path				string				`json:"path" yaml:"path"`
	Args				[]CommandArg	`json:"args" yaml:"args"`
	Env					[]string			`json:"env" yaml:"env"`
	Split				bool					`json:"split" yaml:"split"`
	FailOnError	bool					`json:"failonerror" yaml:"failonerror"`
	StdinAvailable	bool			`json:"stdinavailable,omitempty" yaml:"stdinavailable,omitempty"`
	ExitCode		int							`json:"exitcode,omitempty" yaml:"exitcode,omitempty"`
	Stdout			string						`json:"stdout,omitempty" yaml:"stdout,omitempty"`
	Stderr			string						`json:"stderr,omitempty" yaml:"stderr,omitempty"`
	Executor		CommandExecutor		`json:"-" yaml:"-"`
	Extractor		CommandExtractAttributes	`json:"-" yaml:"-"`
	CommandExists CommandExists		`json:"-" yaml:"-"`
	Input	CommandInput						`json:"-" yaml:"-"`
	stdin	io.Reader								`json:"-" yaml:"-"`

	TargetRef		CommandTargetRef	`json:"targetref,omitempty" yaml:"targetref,omitempty"`
	execHandle	CommandProvider		`json:"-" yaml:"-"`
}

func NewCommand() *Command {
	c := &Command{ Split: true, FailOnError: true }
	c.Defaults()
	return c
}

func (c *Command) ClearOutput() {
	c.Stdout = ""
	c.Stderr = ""
	c.ExitCode = 0
}

func (c *Command) Defaults() {
	c.ClearOutput()
	c.Split = true
	c.FailOnError = true
	c.CommandExists = func() error {
		if _, err := exec.LookPath(c.Path); err != nil {
			return fmt.Errorf("%w - %w", ErrUnknownCommand, err)
		}
		return nil
	}
	c.Executor = func(value any) ([]byte, error) {
		c.ClearOutput()

		c.execHandle = c.TargetRef.Provider(c, value)

		if inputErr := c.SetInput(value); inputErr != nil {
			return nil, inputErr
		}

		c.SetCmdEnv()

		cmd := c.execHandle
		if c.stdin != nil {
			cmd.SetStdin(c.stdin)
		}

		output, stdoutPipeErr := cmd.StdoutPipe()
		if stdoutPipeErr != nil {
			return nil, stdoutPipeErr
		}

		stderr, pipeErr := cmd.StderrPipe()
		if pipeErr != nil {
			return nil, pipeErr
		}

		if startErr := cmd.Start(); startErr != nil {
			return nil, startErr
		}

		slog.Info("execute() - start", "cmd", cmd)
		stdOutOutput, _ := io.ReadAll(output)
		stdErrOutput, _ := io.ReadAll(stderr)
		if len(stdOutOutput) > 100 {
			slog.Info("execute() - io", "stdout", string(stdOutOutput[:100]), "stderr", string(stdErrOutput))
		} else {
			slog.Info("execute() - io", "stdout", string(stdOutOutput), "stderr", string(stdErrOutput))
		}
		waitErr := cmd.Wait()

		c.Stdout = string(stdOutOutput)
		c.Stderr = string(stdErrOutput)
		c.ExitCode = c.GetExitCodeFromError(waitErr)

/*
		if len(stdOutOutput) > 100 {
			slog.Info("execute()", "path", c.Path, "args", args, "output", string(stdOutOutput[:100]), "error", string(stdErrOutput))
		} else {
			slog.Info("execute()", "path", c.Path, "args", args, "output", string(stdOutOutput), "error", string(stdErrOutput))
		}
*/

		if len(stdErrOutput) > 0 && c.FailOnError {
			return stdOutOutput, fmt.Errorf("%w %s", waitErr, string(stdErrOutput))
		}
		return stdOutOutput, waitErr
	}
}

func (c *Command) Load(r io.Reader) error {
	return codec.NewYAMLDecoder(r).Decode(c)
}

func (c *Command) LoadDecl(yamlResourceDeclaration string) error {
	return codec.NewYAMLStringDecoder(yamlResourceDeclaration).Decode(c)
}

func (c *Command) SetCmdEnv() {
	c.execHandle.SetCmdEnv(c.Env)
}

func (c *Command) SetStdinReader(r io.Reader) {
	if c.StdinAvailable {
		c.stdin = r
	}
}

func (c *Command) Exists() bool {
	return c.CommandExists() == nil
}

func (c *Command) GetExitCodeFromError(err error) (ec int) {
	if exitErr, ok := err.(*exec.ExitError); ok {
		if status, ok := exitErr.Sys().(syscall.WaitStatus); ok {
			return status.ExitStatus()
		}
	}
	return
}

func (c *Command) Template(value any) ([]string, error) {
	var args []string = make([]string, 0, len(c.Args) * 2)
	for i, arg := range c.Args {
		var commandLineArg strings.Builder
		err := template.Must(template.New(fmt.Sprintf("arg%d", i)).Parse(string(arg))).Execute(&commandLineArg, value)
		if err != nil {
			return nil, err
		}
		if commandLineArg.Len() > 0 {
			var splitArg []string
			if c.Split {
				splitArg = strings.Split(commandLineArg.String(), " ")
			} else {
				splitArg = []string{commandLineArg.String()}
			}
			slog.Info("Template()", "split", splitArg, "len", len(splitArg))
			args = append(args, splitArg...)
		}
	}
	
	slog.Info("Template()", "Args", c.Args, "lencargs", len(c.Args), "args", args, "lenargs", len(args), "value", value)
	return args, nil
}

func (c *Command) Execute(value any) ([]byte, error) {
	return c.Executor(value)
}

func (c *Command) SetInput(value any) error {
	if len(c.Input) > 0 {
		if r, err := c.Input.Template(value); err != nil {
			slog.Info("Command.SetInput", "input", r.String(), "error", err)
			return err
		} else {
			slog.Info("Command.SetInput", "input", r.String())
			c.SetStdinReader(strings.NewReader(r.String()))
		}
	}
	return nil
}

func (c *CommandInput) Template(value any) (result strings.Builder, err error) {
	err = template.Must(template.New("commandInput").Parse(string(*c))).Execute(&result, value)
	return
}