// Package cli implements the mred command line: a thin, machine-friendly
// front end over the redmine library. Connection settings come from
// MRED_URL / MRED_KEY env vars or a 0600 --config env file — the API key
// is never a flag value and never logged. Every command accepts -o json
// for machine output. Exit codes: 0 ok, 1 usage/config, 2 API error
// (single-line stderr carrying the http status, parseable).
package cli

import (
	"flag"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"

	"git.knownelement.com/ukrrs/mopac-redmine-go/internal/config"
	"git.knownelement.com/ukrrs/mopac-redmine-go/redmine"
)

const usage = `mred: Redmine CLI (stdlib-only, library-backed)

Usage:
  mred issue list -p PROJECT [--status open|all|closed|NAME] [--version NAME] [--limit N] [-o json]
  mred issue show ID [--with journals] [-o json]
  mred issue create -p PROJECT -s SUBJECT [--desc FILE|-] [--tracker NAME]
                    [--priority NAME] [--category NAME] [--version NAME]
                    [--due DATE] [--parent ID] [--est HOURS] [--note TEXT] [-o json]
  mred issue update ID [--status NAME] [--priority NAME] [--category NAME]
                    [--version NAME] [--due DATE] [--done-ratio N]
                    [--desc FILE|-] [--note TEXT] [-o json]
  mred version list -p PROJECT [-o json]
  mred version create -p PROJECT -n NAME [--due DATE] [--status open|closed] [-o json]
  mred category list -p PROJECT [-o json]
  mred category create -p PROJECT -n NAME [-o json]
  mred relation create FROM TO --type blocks|relates [-o json]
  mred help

Connection: MRED_URL + MRED_KEY env vars, or --config PATH pointing at a
0600 env file with the same keys. The API key never appears in flags,
logs, or error output.

Names (--tracker feature, --priority immediate, --status done, --category
and --version) are resolved case-insensitively against the server's own
enumerations; issue ids are numeric.

Exit codes: 0 ok, 1 usage/config error, 2 API error (stderr: one line,
"http NNN" included).`

// Run executes one command; it returns the process exit code.
func Run(args []string, stdout, stderr io.Writer) int {
	if len(args) == 0 {
		fmt.Fprint(stderr, usage)
		return 1
	}
	switch args[0] {
	case "help", "-h", "--help":
		fmt.Fprint(stdout, usage)
		return 0
	case "issue":
		return cmdIssue(args[1:], stdout, stderr)
	case "version":
		return cmdVersion(args[1:], stdout, stderr)
	case "category":
		return cmdCategory(args[1:], stdout, stderr)
	case "relation":
		return cmdRelation(args[1:], stdout, stderr)
	default:
		fmt.Fprintf(stderr, "mred: unknown command %q\n\n%s\n", args[0], usage)
		return 1
	}
}

// newFlags builds a quiet flag set with the shared --config and -o flags.
func newFlags(name string, stderr io.Writer) (*flag.FlagSet, *string, *string) {
	fs := flag.NewFlagSet(name, flag.ContinueOnError)
	fs.SetOutput(io.Discard)
	cfg := fs.String("config", "", "env file with MRED_URL/MRED_KEY (must be 0600)")
	out := fs.String("o", "text", "output format: text|json")
	return fs, cfg, out
}

// parseArgs parses flags that may appear AFTER positionals (the standard
// flag package stops at the first positional; mred's documented surface
// is "issue update ID --note X", "relation create FROM TO --type blocks").
// It returns the positional arguments.
func parseArgs(fs *flag.FlagSet, args []string) ([]string, error) {
	var positionals []string
	rest := args
	for {
		if err := fs.Parse(rest); err != nil {
			return nil, err
		}
		got := fs.Args()
		i := 0
		for i < len(got) && (got[i] == "-" || !strings.HasPrefix(got[i], "-")) {
			i++
		}
		positionals = append(positionals, got[:i]...)
		if i == len(got) {
			return positionals, nil
		}
		rest = got[i:]
	}
}

// client resolves config (env + optional 0600 file) and builds the client.
// A nil client and non-nil error means exit 1; API failures surface later
// as exit 2.
func client(cfgPath string) (*redmine.Client, error) {
	if cfgPath == "" {
		cfgPath = os.Getenv("MRED_CONFIG")
	}
	if cfgPath == "" {
		if home, err := os.UserHomeDir(); err == nil {
			cand := filepath.Join(home, ".config", "mred", "env")
			if _, err := os.Stat(cand); err == nil {
				cfgPath = cand
			}
		}
	}
	cfg, _, err := config.Load(cfgPath)
	if err != nil {
		return nil, err
	}
	return redmine.New(redmine.Config{BaseURL: cfg.BaseURL, APIKey: cfg.APIKey}), nil
}

// apiErr reports an API failure the mred way: one line, exit 2.
func apiErr(stderr io.Writer, err error) int {
	fmt.Fprintf(stderr, "mred: %v\n", err)
	return 2
}

// usageErr reports a usage/config failure: one line, exit 1.
func usageErr(stderr io.Writer, format string, args ...any) int {
	fmt.Fprintf(stderr, "mred: "+format+"\n", args...)
	return 1
}

// emitJSON pretty-prints v for -o json.
func emitJSON(stdout io.Writer, v any) {
	b, err := marshalIndent(v)
	if err != nil {
		return // library types are JSON-clean by construction
	}
	stdout.Write(b)
	fmt.Fprintln(stdout)
}