package api

import (
	"bytes"
	"context"
	"fmt"
	"os"
	"os/exec"
	"strings"
	"time"

	"greq/internal/storage"
)


// RunPreScript executes rf.PreScript before sending the request.
// The script receives REQUEST_URL, REQUEST_METHOD, REQUEST_BODY as env vars.
// Lines of stdout matching "Key: Value" are returned as extra headers to merge
// into the request. A non-zero exit is treated as an error (request is aborted).
func RunPreScript(script string, rf storage.RequestFile, envs map[string]string) (map[string]string, error) {
	if strings.TrimSpace(script) == "" {
		return nil, nil
	}

	out, err := runScript(script, map[string]string{
		"REQUEST_URL":    ResolveVariables(rf.URL, envs),
		"REQUEST_METHOD": rf.Method,
		"REQUEST_BODY":   rf.Body,
	})
	if err != nil {
		return nil, fmt.Errorf("pre_script failed: %w\nOutput: %s", err, out)
	}

	headers := make(map[string]string)
	for _, line := range strings.Split(out, "\n") {
		line = strings.TrimSpace(line)
		if k, v, ok := splitScriptHeader(line); ok {
			headers[k] = v
		}
	}
	return headers, nil
}

// RunTestScript executes the test_script field of a request using the Lua runner.
// See RunLuaTestScript for available globals and helper functions.
func RunTestScript(script string, resp *Response) ([]TestResult, error) {
	return RunLuaTestScript(script, resp)
}

// ---------------------------------------------------------------------------
// Internal helpers
// ---------------------------------------------------------------------------

func runScript(script string, vars map[string]string) (string, error) {
	f, err := os.CreateTemp("", "greq-script-*.sh")
	if err != nil {
		return "", err
	}
	defer os.Remove(f.Name())

	if _, err := f.WriteString("#!/bin/sh\n" + script + "\n"); err != nil {
		f.Close()
		return "", err
	}
	f.Close()

	if err := os.Chmod(f.Name(), 0o700); err != nil {
		return "", err
	}

	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	cmd := exec.CommandContext(ctx, "sh", f.Name())
	// Start with the current process env, then overlay our custom vars
	// so the script has access to PATH, HOME, etc.
	cmd.Env = os.Environ()
	for k, v := range vars {
		cmd.Env = append(cmd.Env, k+"="+v)
	}

	var out bytes.Buffer
	cmd.Stdout = &out
	cmd.Stderr = &out

	err = cmd.Run()
	return out.String(), err
}

func splitScriptHeader(s string) (key, val string, ok bool) {
	idx := strings.Index(s, ": ")
	if idx < 1 {
		return "", "", false
	}
	k := strings.TrimSpace(s[:idx])
	v := strings.TrimSpace(s[idx+2:])
	// Reject lines that look like script output, not headers
	if strings.ContainsAny(k, " \t=/") {
		return "", "", false
	}
	return k, v, true
}