package api

import (
	"encoding/base64"
	"fmt"
	"net/url"
	"sort"
	"strings"
	"unicode"

	"greq/internal/storage"
)

// ImportCURL parses a curl command string into a RequestFile.
// Handles -X, -H/--header, -d/--data/--data-raw, -u/--user, -b/--cookie.
// Unknown placeholder variables ({{…}}) are left as-is.
func ImportCURL(raw string) (storage.RequestFile, error) {
	tokens := tokenizeCURL(raw)
	if len(tokens) == 0 {
		return storage.RequestFile{}, fmt.Errorf("empty input")
	}
	if !strings.EqualFold(tokens[0], "curl") {
		return storage.RequestFile{}, fmt.Errorf("does not start with 'curl'")
	}

	rf := storage.RequestFile{
		Method:  "GET",
		Headers: make(map[string]string),
	}

	i := 1
	for i < len(tokens) {
		tok := tokens[i]
		switch tok {
		case "-X", "--request":
			i++
			if i < len(tokens) {
				rf.Method = strings.ToUpper(tokens[i])
			}
		case "-H", "--header":
			i++
			if i < len(tokens) {
				if k, v, ok := splitHeader(tokens[i]); ok {
					rf.Headers[k] = v
				}
			}
		case "-d", "--data", "--data-raw", "--data-ascii", "--data-urlencode":
			i++
			if i < len(tokens) {
				if rf.Body != "" {
					rf.Body += "&"
				}
				rf.Body += tokens[i]
				if rf.Method == "GET" {
					rf.Method = "POST"
				}
			}
		case "--data-binary":
			i++
			if i < len(tokens) && !strings.HasPrefix(tokens[i], "@") {
				rf.Body = tokens[i]
				if rf.Method == "GET" {
					rf.Method = "POST"
				}
			}
		case "-u", "--user":
			i++
			if i < len(tokens) {
				enc := base64.StdEncoding.EncodeToString([]byte(tokens[i]))
				rf.Headers["Authorization"] = "Basic " + enc
			}
		case "-b", "--cookie":
			i++
			if i < len(tokens) {
				rf.Headers["Cookie"] = tokens[i]
			}
		case "-A", "--user-agent":
			i++
			if i < len(tokens) {
				rf.Headers["User-Agent"] = tokens[i]
			}
		// Flags to silently ignore (no value)
		case "--compressed", "--silent", "-s", "--insecure", "-k",
			"-L", "--location", "-v", "--verbose", "-i", "--include",
			"--no-keepalive", "--http2", "--http1.1", "--http1.0":
		// Short flags with values that we don't handle — skip value
		default:
			if !strings.HasPrefix(tok, "-") {
				if rf.URL == "" {
					rf.URL = tok
				}
			} else if len(tok) == 2 {
				// Unknown short flag: skip its value
				i++
			}
			// Unknown long flags: skip
		}
		i++
	}

	if rf.URL == "" {
		return rf, fmt.Errorf("no URL found in curl command")
	}
	if len(rf.Headers) == 0 {
		rf.Headers = nil
	}
	rf.Name = inferName(rf.Method, rf.URL)
	return rf, nil
}

// ExportCURL builds a shell-safe curl command from a RequestFile.
// Variables are resolved before embedding in the command string.
func ExportCURL(rf storage.RequestFile, envs map[string]string) string {
	var parts []string
	parts = append(parts, "curl")
	parts = append(parts, shellQuote(ResolveVariables(rf.URL, envs)))

	if rf.Method != "GET" || rf.Body != "" {
		parts = append(parts, "-X", rf.Method)
	}

	// Deterministic header order
	keys := make([]string, 0, len(rf.Headers))
	for k := range rf.Headers {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	for _, k := range keys {
		v := ResolveVariables(rf.Headers[k], envs)
		parts = append(parts, "-H", shellQuote(k+": "+v))
	}

	if rf.Body != "" {
		parts = append(parts, "--data-raw", shellQuote(ResolveVariables(rf.Body, envs)))
	}

	return strings.Join(parts, " \\\n  ")
}

// ---------------------------------------------------------------------------
// Internals
// ---------------------------------------------------------------------------

func tokenizeCURL(s string) []string {
	// Join backslash-newline continuations
	s = strings.ReplaceAll(s, "\\\n", " ")
	s = strings.ReplaceAll(s, "\\\r\n", " ")
	s = strings.TrimSpace(s)

	var tokens []string
	var cur strings.Builder
	inSingle := false
	inDouble := false

	for i := 0; i < len(s); i++ {
		c := s[i]
		switch {
		case c == '\'' && !inDouble:
			inSingle = !inSingle
		case c == '"' && !inSingle:
			inDouble = !inDouble
		case c == '\\' && !inSingle:
			i++
			if i < len(s) {
				cur.WriteByte(s[i])
			}
		case (c == ' ' || c == '\t' || c == '\n') && !inSingle && !inDouble:
			if cur.Len() > 0 {
				tokens = append(tokens, cur.String())
				cur.Reset()
			}
		default:
			cur.WriteByte(c)
		}
	}
	if cur.Len() > 0 {
		tokens = append(tokens, cur.String())
	}
	return tokens
}

func splitHeader(s string) (key, val string, ok bool) {
	idx := strings.Index(s, ": ")
	if idx == -1 {
		idx = strings.Index(s, ":")
		if idx == -1 {
			return "", "", false
		}
	}
	return strings.TrimSpace(s[:idx]), strings.TrimSpace(s[idx+1:]), true
}

func inferName(method, rawURL string) string {
	u, err := url.Parse(rawURL)
	if err != nil || u.Path == "" || u.Path == "/" {
		return method + " Request"
	}
	parts := strings.Split(strings.Trim(u.Path, "/"), "/")
	last := parts[len(parts)-1]
	if last == "" || last == "{" {
		return method + " Request"
	}
	// Title-case the last path segment
	words := strings.FieldsFunc(strings.ReplaceAll(last, "_", " "), func(r rune) bool {
		return r == '-' || unicode.IsSpace(r)
	})
	for i, w := range words {
		if len(w) > 0 {
			words[i] = strings.ToUpper(w[:1]) + w[1:]
		}
	}
	return strings.Join(words, " ")
}

// shellQuote wraps s in single quotes, escaping any embedded single quotes.
func shellQuote(s string) string {
	return "'" + strings.ReplaceAll(s, "'", "'\\''") + "'"
}