#!/usr/bin/env bash
# Contract tests for lib/forge-github.sh and lib/forge-forgejo.sh
# (issue #188, term 1). set -u, not -e.
set -u

ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
# shellcheck source=test/harness.sh
. "$ROOT/test/harness.sh"
# shellcheck source=lib/forge.sh
. "$ROOT/lib/forge.sh"

TMP="$(mktemp -d)"
trap 'rm -rf "$TMP"' EXIT

eq() {
  local want="$1" got
  shift
  got="$("$@")" || return 1
  [ "$got" = "$want" ]
}

# --- forge_select: exactly one backend, chosen deliberately -------------

check "select github loads the github backend" 0 "" \
  bash -c '. '"$ROOT"'/lib/forge.sh; forge_select github; declare -f github_page_url >/dev/null'
check "select forgejo loads the forgejo backend" 0 "" \
  bash -c '. '"$ROOT"'/lib/forge.sh; forge_select forgejo; declare -f forgejo_page_url >/dev/null'
check "select refuses an unknown forge" 1 "unknown forge" \
  bash -c '. '"$ROOT"'/lib/forge.sh; forge_select gitlab'
check "select with no argument reads the environment" 0 "" \
  bash -c 'CEREMONY_FORGE=forgejo; . '"$ROOT"'/lib/forge.sh; forge_select; [ "$FORGE" = forgejo ]'

# --- the page-size contract, both dialects ------------------------------
# The trap, measured 2026-08-02: each forge silently ignores the OTHER's
# page-size parameter and answers HTTP 200 with fewer items.
#
#   ?per_page=100   GitHub 100   Forgejo 30  (ignored)
#   ?limit=100      GitHub  30   Forgejo 50  (capped)
#
# So no call site names one, and these two functions are the only places
# that decide. Pure on purpose: the contract is testable without a network.

. "$ROOT/lib/forge-github.sh"
. "$ROOT/lib/forge-forgejo.sh"

check "github: a bare path gets a query" 0 "" \
  eq 'repos/o/r/issues?per_page=100' github_page_url 'repos/o/r/issues'
check "github: an existing query is preserved" 0 "" \
  eq 'repos/o/r/issues?state=open&per_page=100' github_page_url 'repos/o/r/issues?state=open'
check "forgejo: a bare path gets a query" 0 "" \
  eq 'repos/o/r/issues?limit=50&page=1' forgejo_page_url 'repos/o/r/issues' 1
check "forgejo: an existing query is preserved" 0 "" \
  eq 'repos/o/r/issues?state=open&limit=50&page=2' forgejo_page_url 'repos/o/r/issues?state=open' 2

# A caller that names a page size anyway must not be able to reintroduce the
# truncation — the parameter is stripped in BOTH dialects, on both backends,
# because the whole point is that the boundary decides and the call site
# cannot override it by accident.
check "github strips a stray per_page" 0 "" \
  eq 'repos/o/r/issues?state=open&per_page=100' github_page_url 'repos/o/r/issues?state=open&per_page=30'
check "github strips a stray limit" 0 "" \
  eq 'repos/o/r/issues?state=open&per_page=100' github_page_url 'repos/o/r/issues?state=open&limit=100'
check "forgejo strips a stray per_page" 0 "" \
  eq 'repos/o/r/issues?state=open&limit=50&page=1' forgejo_page_url 'repos/o/r/issues?state=open&per_page=100' 1
check "forgejo strips a stray limit" 0 "" \
  eq 'repos/o/r/issues?state=open&limit=50&page=1' forgejo_page_url 'repos/o/r/issues?state=open&limit=100' 1
check "stripping the only parameter leaves a clean query" 0 "" \
  eq 'repos/o/r/issues?limit=50&page=1' forgejo_page_url 'repos/o/r/issues?per_page=100' 1

# --- the forgejo gather: complete, or loudly refused --------------------
# curl is stubbed as a function so these are hermetic. Each case writes the
# headers and body a real Forgejo would.

# fake_forge <total> <pages…> — install a curl stub serving <pages> as
# successive page bodies, declaring <total> in x-total-count. An empty
# string for <total> omits the header entirely (@kimi's #4699 case).
fake_forge() {
  FAKE_TOTAL="$1"; shift
  FAKE_PAGES=("$@")
  FAKE_CALLS=0
  curl() {
    local hdr="" out="" url=""
    while [ $# -gt 0 ]; do
      case "$1" in
        -D) hdr="$2"; shift ;;
        -o) out="$2"; shift ;;
        -H) shift ;;
        -*) ;;
        *) url="$1" ;;
      esac
      shift
    done
    local page=1
    case "$url" in *page=*) page="${url##*page=}"; page="${page%%&*}" ;; esac
    {
      printf 'HTTP/1.1 200 OK\r\n'
      [ -n "$FAKE_TOTAL" ] && printf 'X-Total-Count: %s\r\n' "$FAKE_TOTAL"
      printf '\r\n'
    } >"$hdr"
    if [ "$page" -le "${#FAKE_PAGES[@]}" ]; then
      printf '%s' "${FAKE_PAGES[$((page - 1))]}" >"$out"
    else
      printf '[]' >"$out"
    fi
    FAKE_CALLS=$((FAKE_CALLS + 1))
    return 0
  }
}

export CEREMONY_FORGE_API=https://forge.example/api/v1

# One page, and the count agrees with the declared total.
fake_forge 2 '[{"number":1},{"number":2}]'
check "a complete single-page gather returns its items" 0 "" \
  eq $'1\n2' forge_api --paginate 'repos/o/r/issues' --jq '.[].number'

# Two pages that add up. The walk must not stop at the first page merely
# because it came back non-empty — rig has 137 issues across 3 pages, which
# is the case this models.
fake_forge 4 '[{"number":1},{"number":2}]' '[{"number":3},{"number":4}]'
check "a multi-page gather walks every page" 0 "" \
  eq $'1\n2\n3\n4' forge_api --paginate 'repos/o/r/issues' --jq '.[].number'

# The whole reason the assert exists: a server that declares more than it
# hands over must not produce a "successful" partial sweep.
fake_forge 137 '[{"number":1},{"number":2}]'
check "a short gather is refused, not reconciled" 1 "incomplete gather" \
  forge_api --paginate 'repos/o/r/issues' --jq '.[].number'
check "...and the refusal names both counts" 1 "collected 2 of 137" \
  forge_api --paginate 'repos/o/r/issues' --jq '.[].number'

# @kimi-reviewer-andresmgsl's hardening (#4699): the guard must not be able
# to degrade silently either. A Forgejo that does not expose x-total-count
# leaves the assert with nothing to compare, and an assert that cannot run
# must refuse rather than pass.
fake_forge '' '[{"number":1},{"number":2}]'
check "a missing x-total-count refuses" 1 "did not send x-total-count" \
  forge_api --paginate 'repos/o/r/issues' --jq '.[].number'
check "...and says why it cannot prove completeness" 1 "cannot prove the gather is complete" \
  forge_api --paginate 'repos/o/r/issues' --jq '.[].number'

# --- HTTP failures are named, not swallowed -----------------------------
# gh exits non-zero on an HTTP error; curl does not without -f, and -f
# discards the body that explains why. So the status is read explicitly.
fake_forge 1 '[{"number":1}]'
curl() {
  local hdr="" out=""
  while [ $# -gt 0 ]; do
    case "$1" in -D) hdr="$2"; shift ;; -o) out="$2"; shift ;; esac
    shift
  done
  printf 'HTTP/1.1 404 Not Found\r\n\r\n' >"$hdr"
  printf '{"message":"Not found"}' >"$out"
  return 0
}
check "a 404 is a named failure" 1 "HTTP 404" forge_api 'repos/o/r/issues/9999'
check "a 404 names the endpoint" 1 "repos/o/r/issues/9999" forge_api 'repos/o/r/issues/9999'

# --- the api base must be known -----------------------------------------
check "no api base refuses" 1 "cannot reach the forge" \
  bash -c 'unset CEREMONY_FORGE_API GITHUB_API_URL; . '"$ROOT"'/lib/forge-forgejo.sh; forgejo_api_base'

summary